refactor(ui): 删除不再使用的UI组件

清理代码库中不再使用的UI组件，包括FrostedGlass、SearchBar、CourseCard、GradientHeader、LiveStreamCard、SummerCampCard和ActivityCard。这些组件在当前项目中已无作用，删除以保持代码简洁。

-import React from 'react';
-import { Link } from 'react-router-dom';
-import FrostedGlass from './FrostedGlass';
-
-/**
- * ActivityCard component displays an activity item in the activities list
- * 
- * @param {Object} props - Component props
- * @param {Object} props.activity - Activity data
- * @returns {JSX.Element} ActivityCard component
- */
-const ActivityCard = ({ activity }) => {
-  // Function to get the appropriate status class
-  const getStatusClass = (status) => {
-    switch (status) {
-      case '活动中':
-        return 'bg-blue-100 text-blue-600';
-      case '进行中':
-        return 'bg-green-100 text-green-600';
-      case '即将开始':
-        return 'bg-orange-100 text-orange-600';
-      case '已结束':
-        return 'bg-gray-100 text-gray-600';
-      default:
-        return 'bg-gray-100 text-gray-600';
-    }
-  };
-  
-  return (
-    <Link to={`/activities/${activity.id}`}>
-      <FrostedGlass className="flex overflow-hidden rounded-xl shadow-sm">
-        {/* Activity Image */}
-        <div className="w-1/3 h-28 relative">
-          <img
-            src={activity.imageUrl}
-            alt={activity.title}
-            className="w-full h-full object-cover"
-          />
-          {activity.isHot && (
-            <div className="absolute top-0 left-0 bg-red-500 text-white text-xs px-2 py-0.5">
-              热门
-            </div>
-          )}
-        </div>
-        
-        {/* Activity Info */}
-        <div className="flex-1 p-3 flex flex-col justify-between">
-          <div>
-            <h3 className="font-medium text-base mb-1 line-clamp-1">{activity.title}</h3>
-            
-            {/* Status Tags */}
-            <div className="flex items-center space-x-2 mb-1">
-              <span className={`px-2 py-0.5 rounded-full text-xs ${getStatusClass(activity.status)}`}>
-                {activity.status}
-              </span>
-              {activity.isFree && (
-                <span className="px-2 py-0.5 rounded-full text-xs bg-green-100 text-green-600">
-                  免费
-                </span>
-              )}
-            </div>
-          </div>
-          
-          {/* Location and Time */}
-          <div className="text-xs text-gray-500 space-y-1">
-            <div className="flex items-center">
-              <svg xmlns="http://www.w3.org/2000/svg" className="h-3.5 w-3.5 mr-1" fill="none" viewBox="0 0 24 24" stroke="currentColor">
-                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17.657 16.657L13.414 20.9a1.998 1.998 0 01-2.827 0l-4.244-4.243a8 8 0 1111.314 0z" />
-                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 11a3 3 0 11-6 0 3 3 0 016 0z" />
-              </svg>
-              <span>{activity.location}</span>
-            </div>
-            
-            <div className="flex items-center">
-              <svg xmlns="http://www.w3.org/2000/svg" className="h-3.5 w-3.5 mr-1" fill="none" viewBox="0 0 24 24" stroke="currentColor">
-                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M8 7V3m8 4V3m-9 8h10M5 21h14a2 2 0 002-2V7a2 2 0 00-2-2H5a2 2 0 00-2 2v12a2 2 0 002 2z" />
-              </svg>
-              <span>{activity.period}</span>
-            </div>
-          </div>
-          
-          {/* Bottom Info Section */}
-          <div className="mt-1 flex items-center justify-between">
-            {activity.price ? (
-              <div className="flex items-baseline">
-                <span className="text-red-500 font-medium">¥{activity.price}</span>
-                {activity.originalPrice && (
-                  <span className="text-xs text-gray-400 ml-1 line-through">¥{activity.originalPrice}</span>
-                )}
-              </div>
-            ) : (
-              <div></div> // Empty div for spacing when no price
-            )}
-            
-            <div className="flex items-center text-xs text-gray-500">
-              <svg xmlns="http://www.w3.org/2000/svg" className="h-3.5 w-3.5 mr-1" fill="none" viewBox="0 0 24 24" stroke="currentColor">
-                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17 20h5v-2a3 3 0 00-5.356-1.857M17 20H7m10 0v-2c0-.656-.126-1.283-.356-1.857M7 20H2v-2a3 3 0 015.356-1.857M7 20v-2c0-.656.126-1.283.356-1.857m0 0a5.002 5.002 0 019.288 0M15 7a3 3 0 11-6 0 3 3 0 016 0zm6 3a2 2 0 11-4 0 2 2 0 014 0zM7 10a2 2 0 11-4 0 2 2 0 014 0z" />
-              </svg>
-              <span>{activity.participantsCount || '15'}/{activity.maxParticipants || '30'}</span>
-            </div>
-          </div>
-        </div>
-      </FrostedGlass>
-    </Link>
-  );
-};
-
-export default ActivityCard;
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-import React from 'react';
-import { Link } from 'react-router-dom';
-
-/**
- * CourseCard component displays a course item in the course list
- * 
- * @param {Object} props - Component props
- * @param {Object} props.course - Course data
- * @returns {JSX.Element} CourseCard component
- */
-const CourseCard = ({ course }) => {
-  return (
-    <Link to={`/courses/${course.id}`} className="flex bg-white rounded-lg overflow-hidden shadow-sm">
-      <div className="w-1/3 h-28">
-        <img 
-          src={course.imageUrl} 
-          alt={course.title}
-          className="w-full h-full object-cover"
-        />
-      </div>
-      <div className="flex-1 p-3 flex flex-col justify-between">
-        <div>
-          <h3 className="font-medium text-sm mb-1 line-clamp-2">{course.title}</h3>
-          <div className="text-gray-500 text-xs">{course.subtitle}</div>
-        </div>
-        <div className="flex justify-between items-end mt-1">
-          <div className="text-orange-500 font-semibold">¥{course.price}</div>
-          <div className="text-gray-400 text-xs">
-            {course.subscribers}人订阅
-          </div>
-        </div>
-        <div className="text-gray-400 text-xs">
-          已更新{course.updatedLessons}期 | {course.subscribers}人订阅
-        </div>
-      </div>
-    </Link>
-  );
-};
-
-export default CourseCard;
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-import React from 'react';
-
-/**
- * FrostedGlass component creates a container with a frosted glass effect
- * using backdrop-filter blur and a semi-transparent white background.
- * 
- * @param {Object} props - Component props
- * @param {ReactNode} props.children - Child elements
- * @param {string} props.className - Additional CSS classes
- * @returns {JSX.Element} FrostedGlass component
- */
-const FrostedGlass = ({ children, className = '' }) => {
-  return (
-    <div 
-      className={`bg-white/20 backdrop-blur-md rounded-xl border border-white/30 
-                 shadow-lg ${className}`}
-    >
-      {children}
-    </div>
-  );
-};
-
-export default FrostedGlass;
\ No newline at end of file

-import React from 'react';
-
-/**
- * GradientHeader component for page headers with gradient background
- * and navigation elements.
- * 
- * @param {Object} props - Component props
- * @param {string} props.title - Header title
- * @param {boolean} props.showBackButton - Whether to show back button
- * @param {Function} props.onBack - Back button click handler
- * @param {ReactNode} props.rightContent - Content to display on the right side
- * @returns {JSX.Element} GradientHeader component
- */
-const GradientHeader = ({ title, showBackButton = false, onBack, rightContent }) => {
-  return (
-    <header className="bg-gradient-to-r from-green-50 to-blue-50 p-4 relative">
-      <div className="flex items-center justify-between">
-        {showBackButton && (
-          <button 
-            onClick={onBack} 
-            className="p-2 rounded-full bg-white/30 backdrop-blur-sm"
-            aria-label="返回"
-          >
-            <svg xmlns="http://www.w3.org/2000/svg" className="h-5 w-5 text-gray-700" fill="none" viewBox="0 0 24 24" stroke="currentColor">
-              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 19l-7-7 7-7" />
-            </svg>
-          </button>
-        )}
-        <h1 className={`text-xl font-medium text-center ${showBackButton ? 'flex-1' : ''}`}>
-          {title}
-        </h1>
-        {rightContent && <div>{rightContent}</div>}
-      </div>
-    </header>
-  );
-};
-
-export default GradientHeader;
\ No newline at end of file

-import React from 'react';
-import { Link } from 'react-router-dom';
-
-/**
- * LiveStreamCard component displays a live stream in the courses page
- * 
- * @param {Object} props - Component props
- * @param {Object} props.stream - Stream data
- * @returns {JSX.Element} LiveStreamCard component
- */
-const LiveStreamCard = ({ stream }) => {
-  return (
-    <div className="relative">
-      {/* Live indicator */}
-      <div className="absolute top-2 left-2 bg-red-500/90 text-white text-xs px-2 py-1 rounded flex items-center z-10">
-        <div className="w-2 h-2 bg-white rounded-full mr-1 animate-pulse"></div>
-        直播中
-      </div>
-      
-      <Link to={`/courses/${stream.id}`} className="block rounded-lg overflow-hidden shadow-sm relative">
-        <img 
-          src={stream.imageUrl} 
-          alt={stream.title} 
-          className="w-full h-28 object-cover"
-        />
-        
-        {/* Gradient overlay */}
-        <div className="absolute inset-0 bg-gradient-to-b from-transparent to-black/60"></div>
-        
-        {/* Stream info */}
-        <div className="absolute bottom-2 left-2 right-2">
-          <h3 className="text-white text-sm font-medium">「{stream.title}」{stream.subtitle}</h3>
-          <div className="flex items-center mt-1">
-            <div className="flex -space-x-2">
-              <div className="w-5 h-5 rounded-full bg-gray-300 border border-white"></div>
-              <div className="w-5 h-5 rounded-full bg-gray-400 border border-white"></div>
-              <div className="w-5 h-5 rounded-full bg-gray-500 border border-white"></div>
-            </div>
-            <span className="text-white text-xs ml-1">{stream.viewers}人在看</span>
-            <button className="ml-auto bg-green-500 text-white text-xs px-2 py-1 rounded">
-              立即观看
-            </button>
-          </div>
-        </div>
-      </Link>
-    </div>
-  );
-};
-
-export default LiveStreamCard;
\ No newline at end of file

-import React from 'react';
-import FrostedGlass from './FrostedGlass';
-
-/**
- * SearchBar component with frosted glass effect
- * 
- * @param {Object} props - Component props
- * @param {string} props.placeholder - Placeholder text
- * @param {Function} props.onSearch - Search callback function
- * @returns {JSX.Element} SearchBar component
- */
-const SearchBar = ({ placeholder = '搜索', onSearch }) => {
-  return (
-    <FrostedGlass className="px-4 py-2 mx-4 my-3 flex items-center">
-      <svg xmlns="http://www.w3.org/2000/svg" className="h-5 w-5 text-gray-400 mr-2" fill="none" viewBox="0 0 24 24" stroke="currentColor">
-        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M21 21l-6-6m2-5a7 7 0 11-14 0 7 7 0 0114 0z" />
-      </svg>
-      <input
-        type="text"
-        placeholder={placeholder}
-        className="bg-transparent outline-none flex-1 text-gray-700 placeholder-gray-400"
-        onChange={(e) => onSearch && onSearch(e.target.value)}
-      />
-    </FrostedGlass>
-  );
-};
-
-export default SearchBar;
\ No newline at end of file

-import React from 'react';
-import PropTypes from 'prop-types';
-
-/**
- * SummerCampCard component - displays summer camp information with image background
- * @param {Object} props - Component props
- * @returns {JSX.Element} - Rendered component
- */
-const SummerCampCard = ({ 
-  title = "大国少年-世界正东方", 
-  subtitle = "亲子夏令营", 
-  badge = "亲子夏令营", 
-  price = "¥1280", 
-  discount = "限时优惠", 
-  episodes = 16, 
-  subscribers = 1140 
-}) => {
-  return (
-    <div className="relative overflow-hidden rounded-b-3xl shadow-lg">
-      {/* Background image with overlay */}
-      <div 
-        className="absolute inset-0 z-0 bg-cover bg-center" 
-        style={{ 
-          backgroundImage: `url('/assets/images/summer-camp.jpg')`,
-          filter: 'brightness(0.4)'
-        }}
-      ></div>
-      
-      {/* Gradient overlay */}
-      <div className="absolute inset-0 z-1 bg-gradient-to-b from-red-500/70 to-red-600/90"></div>
-      
-      {/* Content */}
-      <div className="relative z-10 p-4">
-        <div className="bg-white/10 backdrop-blur-sm rounded-lg p-3 mb-3 inline-block">
-          <div className="text-white font-semibold">{badge}</div>
-        </div>
-        
-        <h1 className="text-2xl text-white font-bold mb-1">{title}</h1>
-        <h2 className="text-lg text-white/90">{subtitle}</h2>
-        
-        <div className="mt-4 flex justify-between items-center">
-          <div className="text-orange-300 font-bold text-2xl">{price}</div>
-          <div className="bg-orange-500/30 text-orange-100 text-xs px-3 py-1 rounded-full">{discount}</div>
-        </div>
-        
-        <div className="flex justify-between text-xs text-white/80 mt-3">
-          <div>已更新{episodes}期</div>
-          <div>{subscribers}人订阅</div>
-        </div>
-      </div>
-    </div>
-  );
-};
-
-SummerCampCard.propTypes = {
-  title: PropTypes.string,
-  subtitle: PropTypes.string,
-  badge: PropTypes.string,
-  price: PropTypes.string,
-  discount: PropTypes.string,
-  episodes: PropTypes.number,
-  subscribers: PropTypes.number
-};
-
-export default SummerCampCard;
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