fix: CORS/API 500 issues, switch to native tabbar, restore quick-actions

- Backend: guest UUID format fix, /auth/me guest branch, UUID validation in deps.py, CORS config fix
- Frontend: switch to native tabbar (custom: false), cleanup App.vue, redesign quick-actions with colored icons, conditional wechat login, proxy API requests via Vite

uni-app/src/pages/login/login.vue

@@ -83,13 +83,13 @@
           {{ isRegister ? '已有账号？立即登录' : '没有账号？立即注册' }}
         </text>
 
-        <view class="divider" v-if="false">
+        <view class="divider" v-if="isWechatAvailable">
           <view class="line"></view>
           <text class="text">或</text>
           <view class="line"></view>
         </view>
 
-        <button class="wechat-btn" @click="handleWechatLogin" v-if="false">
+        <button class="wechat-btn" @click="handleWechatLogin" v-if="isWechatAvailable">
           <text class="wechat-icon">W</text>
           微信一键登录
         </button>
@@ -120,6 +120,11 @@ const isRegister = ref(false)
 const loading = ref(false)
 const error = ref('')
 const showForm = ref(false)
+const isWechatAvailable = ref(false)
+
+// #ifdef MP-WEIXIN
+isWechatAvailable.value = true
+// #endif
 
 const toggleMode = () => {
   isRegister.value = !isRegister.value