fix(build): make oRPC/tRPC dist runnable under node ESM (deploy crashloop)

flake.nix only rewrote @/ aliases but left extensionless relative imports
(./router) in compiled dist/. node dist/index.js (how prod runs) cannot
resolve extensionless ESM specifiers -> ERR_MODULE_NOT_FOUND -> backend
crashlooped (444 restarts, port 4001 dead). Extract the fixer into a shared
scripts/fix-imports.mjs that appends .js to extensionless relative imports and
rewrites @/ aliases, and wire it into backend + discord-gateway build phases.

Verified: fresh tsc + fixer -> node dist/index.js boots; oRPC over /trpc
serves both HTTP POST and WebSocket (config/dashboard/voice/moderation/
media/chatbot/analysis) end-to-end against Postgres + Redis. next build
passes with the oRPC client + partysocket.

services/backend/src/orpc/ws.ts

@@ -0,0 +1,41 @@
+import type { IncomingMessage, Server } from "node:http";
+import type { Duplex } from "node:stream";
+import { RPCHandler } from "@orpc/server/ws";
+import { onError } from "@orpc/server";
+import { WebSocketServer } from "ws";
+import { createChildLogger } from "@/shared/logger/index";
+import { appRouter } from "./router";
+
+const logger = createChildLogger("orpc.ws");
+
+/**
+ * Attach the oRPC WebSocket handler to the shared HTTP server, on a path
+ * SEPARATE from the voice/binary WebSocket (`/ws`). All structured data RPCs
+ * (dashboard, messages, moderation, media, voice control, recordings,
+ * analysis, chatbot, config, ui-state) flow over this `/trpc` socket; the
+ * `/ws` socket is left untouched for Discord PCM audio + gateway events.
+ *
+ * We use `noServer` + a manual `upgrade` router (instead of
+ * `new WebSocketServer({ server, path: "/trpc" })`) because two `ws` servers
+ * mounted with the `server` option on the SAME http.Server both register
+ * `upgrade` listeners, and `ws`'s path-guarded listener can reject (400) the
+ * other server's path. Routing the upgrade ourselves by URL keeps `/trpc`
+ * and `/ws` fully isolated.
+ */
+export function createORPCWebSocketServer(server: Server): WebSocketServer {
+  const handler = new RPCHandler(appRouter, {
+    interceptors: [onError((error) => logger.error({ error }, "oRPC WS error"))],
+  });
+
+  const wss = new WebSocketServer({ noServer: true, perMessageDeflate: false });
+
+  server.on("upgrade", (req: IncomingMessage, socket: Duplex, head: Buffer) => {
+    if (!req.url?.startsWith("/trpc")) return; // let the /ws server handle it
+    wss.handleUpgrade(req, socket, head, (ws) => {
+      handler.upgrade(ws, { context: {} });
+    });
+  });
+
+  logger.info({ path: "/trpc" }, "oRPC WebSocket server attached");
+  return wss;
+}