style(CreateFamily): 将禁用按钮背景色从gray-400改为gray-300以提升视觉一致性

 <!--
  * @Date: 2025-08-27 17:44:53
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-08-28 21:35:16
+ * @LastEditTime: 2025-08-29 10:37:54
  * @FilePath: /lls_program/src/pages/CreateFamily/index.vue
  * @Description: 文件描述
 -->
@@ -143,7 +143,7 @@
         @tap="isFormValid ? handleCreateFamily : null"
         :class="[
           'w-full py-3 text-white text-lg font-medium rounded-lg flex items-center justify-center',
-          isFormValid ? 'bg-blue-500' : 'bg-gray-400'
+          isFormValid ? 'bg-blue-500' : 'bg-gray-300'
         ]"
       >
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