fix: redirect /login to / when AUTH_ENABLED=false (#3235)

app.py

@@ -784,6 +784,8 @@ async def serve_backgrounds(request: Request):
 
 @app.get("/login")
 async def serve_login(request: Request):
+    if not AUTH_ENABLED:
+        return RedirectResponse(url="/", status_code=302)
     return _serve_html_with_nonce(request, abs_join(BASE_DIR, "static/login.html"))
 
 @app.get("/api/version")