fix(infra): add JWT_SECRET to stream-server in production compose

SEC-05: stream-server was missing JWT_SECRET while chat-server had it.
Both services need the shared secret to validate tokens.

docker-compose.prod.yml

@@ -218,6 +218,7 @@ services:
     environment:
       - DATABASE_URL=postgres://${DB_USER:-veza}:${DB_PASS:?DB_PASS must be set}@postgres:5432/${DB_NAME:-veza}?sslmode=require
       - REDIS_URL=redis://:${REDIS_PASSWORD:?REDIS_PASSWORD must be set}@redis:6379
+      - JWT_SECRET=${JWT_SECRET:?JWT_SECRET must be set}
       - PORT=3001
     depends_on:
       postgres: