fix(Welcome): 修复年龄计算逻辑并添加创建家庭条件检查

修正生日到年龄的转换逻辑，考虑月份和日期差异
添加满60岁才能创建家庭的检查

@@ -209,11 +209,29 @@ useDidShow(async () => {
       wheelchair_text: null,
       phone: null,
     };
-    // userInfo.birthday 是年月日的形式需要转成年龄
-    userInfo.value.birthday = new Date().getFullYear() - new Date(userInfo.value.birth_date).getFullYear();
+    
+    // 计算用户年龄
+    if (userInfo.value.birth_date) {
+      const birthDate = new Date(userInfo.value.birth_date);
+      const today = new Date();
+      let age = today.getFullYear() - birthDate.getFullYear();
+      const monthDiff = today.getMonth() - birthDate.getMonth();
+      
+      // 如果还没到生日，年龄减1
+      if (monthDiff < 0 || (monthDiff === 0 && today.getDate() < birthDate.getDate())) {
+        age--;
+      }
+      
+      userAge.value = age;
+      // 检查是否满60岁，可以创建家庭
+      canCreateFamily.value = age >= 60;
+    } else {
+      userAge.value = null;
+      canCreateFamily.value = false;
+    }
+    
     // 检查用户是否完善了个人信息
     hasProfile.value = userInfo.value.nickname && userInfo.value.birth_date && userInfo.value.wheelchair_needed !== null;
-    userAge.value = userInfo.value.birthday;
   }
 });