feat(root): merge phase-b — admin endpoints, rate limiting, redis integration

Author: gahyun-git

apps/api/.env.example

@@ -21,9 +21,12 @@ BETTER_AUTH_URL=http://localhost:3200
 # JWT (stateless authentication)
 JWT_SECRET=your-super-secret-jwt-key-change-in-production
 
-# Redis (optional)
+# Redis (rate limiting, optional)
 REDIS_URL=redis://localhost:6380
 
+# Internal service auth (Worker → API)
+INTERNAL_API_KEY=your-internal-api-key-change-in-production
+
 # LiveKit (optional)
 LIVEKIT_API_URL=
 LIVEKIT_API_KEY=