feat(iios): socket.io Redis adapter for cross-replica realtime (P9 scaling)

Adds an opt-in RedisIoAdapter (wired in main.ts when REDIS_URL is set) so
socket.io room emits fan out across instances via Redis pub/sub — a client on
replica B now receives messages emitted by replica A. Without REDIS_URL the
in-memory adapter is kept (single-instance dev unchanged). Adds redis to
docker-compose, REDIS_URL to the env contract, and smoke-realtime-cluster.mjs
which proves cross-instance delivery fails without Redis and passes with it.
Delivery is at-least-once at N>1; clients dedupe by message id (documented).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/iios-service/package.json

@@ -12,22 +12,24 @@
     "prisma:studio": "prisma studio"
   },
   "dependencies": {
-    "@insignia/iios-contracts": "workspace:*",
     "@insignia/iios-adapter-sdk": "workspace:*",
+    "@insignia/iios-contracts": "workspace:*",
     "@nestjs/common": "^11.1.27",
     "@nestjs/core": "^11.1.27",
     "@nestjs/platform-express": "^11.1.27",
     "@nestjs/platform-socket.io": "^11.1.27",
     "@nestjs/websockets": "^11.1.27",
     "@prisma/client": "^6.2.1",
-    "prisma": "^6.2.1",
-    "socket.io": "^4.8.3",
+    "@socket.io/redis-adapter": "^8.3.0",
     "class-transformer": "^0.5.1",
     "class-validator": "^0.15.1",
     "dotenv": "^16.4.7",
+    "ioredis": "^5.11.1",
     "jsonwebtoken": "^9.0.3",
+    "prisma": "^6.2.1",
     "reflect-metadata": "^0.2.2",
-    "rxjs": "^7.8.2"
+    "rxjs": "^7.8.2",
+    "socket.io": "^4.8.3"
   },
   "devDependencies": {
     "@insignia/iios-testkit": "workspace:*",