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/App.vue

@@ -20,26 +20,12 @@ html, body, #app {
   width: 100%;
 }
 
-/* Fix: make uni-page scrollable and properly sized for fixed tabbar */
+/* Let uni-app framework manage layout for native tabbar */
 uni-page {
-  height: calc(100% - 50px) !important;
   overflow-y: auto !important;
-  overflow-x: hidden !important;
-  -webkit-overflow-scrolling: touch !important;
 }
-uni-page-body, uni-page-wrapper {
+uni-page-body {
   overflow-y: auto !important;
-  overflow-x: hidden !important;
-  -webkit-overflow-scrolling: touch !important;
-}
-
-/* Ensure the page head doesn't block scrolling */
-uni-page-head {
-  flex-shrink: 0;
-}
-
-/* The uni-tabbar is already position:fixed by the framework */
-uni-tabbar {
-  z-index: 999 !important;
+  min-height: 100% !important;
 }
 </style>