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>

stop-all.sh

@@ -3,8 +3,10 @@
 
 echo "🛑 停止所有服务..."
 
-docker compose -f docker-compose.backend.yml down
 docker compose -f docker-compose.dev.yml down
 docker compose -f docker-compose.uat.yml down
 
+# 清理旧名称的残留容器
+docker rm -f gamegroup-livekit gamegroup-voice-token 2>/dev/null || true
+
 echo "✅ 所有服务已停止"