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

backend/app/main.py

@@ -31,11 +31,12 @@ app = FastAPI(
     version="1.0.0",
     docs_url="/docs",
     redoc_url="/redoc",
+    debug=settings.DEBUG,
 )
 
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=[settings.FRONTEND_URL, "*"],
+    allow_origins=[settings.FRONTEND_URL],
     allow_credentials=True,
     allow_methods=["*"],
     allow_headers=["*"],