fix: correctly call websocket_endpoint from _WSInterceptMiddleware

The middleware was calling the handler as a raw ASGI callable
(scope, receive, send), but websocket_endpoint expects (WebSocket, token).
This caused an AttributeError on every connection attempt, which made the
frontend hit its 30s exponential backoff cap and spam reconnects.

Fix: construct a WebSocket object from scope/receive/send and extract the
?token= query param before calling the handler, matching what FastAPI's
routing machinery would do.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/app.py

@@ -88,7 +88,11 @@ class _WSInterceptMiddleware:
 
     async def __call__(self, scope, receive, send) -> None:
         if scope["type"] == "websocket" and scope.get("path") == "/ws":
-            await self._ws(scope, receive, send)
+            from urllib.parse import parse_qs
+            from starlette.websockets import WebSocket as _WS
+            qs = parse_qs(scope.get("query_string", b"").decode())
+            token = qs.get("token", [""])[0]
+            await self._ws(_WS(scope, receive=receive, send=send), token)
         else:
             await self._app(scope, receive, send)