Browser connects oRPC over wss://…/trpc (partysocket). The gmw-proxy nginx
only forwarded /api and /ws to the backend, so /trpc upgrades fell through to
Next.js SSR and the socket never opened ("WebSocket is not open"). Add a
/trpc location (WS upgrade headers) mirroring /ws. Backend already serves
oRPC on /trpc (HTTP RPCHandler + WS ORPCWebSocketServer on :4001).
Verified: ws://127.0.0.1:4001/trpc upgrade OPEN; SSR + server-side fetch RPCLink
also use /trpc directly so only the browser path was broken.