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/frontend/package.json

@@ -10,12 +10,13 @@
     "format": "biome format --write"
   },
   "dependencies": {
-    "@trpc/client": "^11.18.0",
+    "@orpc/client": "1.15.0",
     "clsx": "^2.1.1",
     "lucide-react": "^1.27.0",
     "motion": "^12.0.0",
     "next": "16.2.12",
     "next-themes": "^0.4.6",
+    "partysocket": "1.3.0",
     "react": "19.2.4",
     "react-dom": "19.2.4",
     "swr": "^2.4.2",