refactor(deploy): separate Dev/UAT into independent full-stack environments

- Each environment now runs its own PB + LiveKit + Voice Token + frontend
- UAT LiveKit: 7890, Voice Token: 7893 (separate from Dev 7880/7883)
- Remove docker-compose.backend.yml, merge into dev compose
- Delete duplicate bulletin migration files that caused PB crash on startup
- Update CLAUDE.md, nginx configs, and .env files accordingly

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docker-compose.uat.yml

@@ -20,13 +20,13 @@ services:
     networks:
       - gamegroup-net
 
-  livekit:
+  livekit-uat:
     image: livekit/livekit-server:v1.10
-    container_name: gamegroup-livekit
+    container_name: gamegroup-livekit-uat
     ports:
-      - "7880:7880"
-      - "7881:7881/udp"
-      - "7882:7882/udp"
+      - "7890:7880"
+      - "7891:7881/udp"
+      - "7892:7882/udp"
     environment:
       LIVEKIT_KEYS: "APIyxZGQjM2: secretNmU4ZDU3YjA0OWIxNDM4YjhlNWY3YTFjZGUzOWRi"
     command: --dev --node-ip 192.168.1.14
@@ -34,12 +34,12 @@ services:
     networks:
       - gamegroup-net
 
-  voice-token:
+  voice-token-uat:
     build:
       context: ./backend/voice-token-service
-    container_name: gamegroup-voice-token
+    container_name: gamegroup-voice-token-uat
     ports:
-      - "7882:7882"
+      - "7893:7882"
     environment:
       - LIVEKIT_API_KEY=APIyxZGQjM2
       - LIVEKIT_API_SECRET=secretNmU4ZDU3YjA0OWIxNDM4YjhlNWY3YTFjZGUzOWRi