fix(mpc-service): 添加 MPC_COORDINATOR_URL 和 MPC_MESSAGE_ROUTER_WS_URL 配置

问题：mpc-service 的 MPCCoordinatorClient 需要 MPC_COORDINATOR_URL 环境变量
原本只配置了 MPC_SESSION_COORDINATOR_URL，导致 Invalid URL 错误

修改内容：
- docker-compose.yml: 添加 MPC_COORDINATOR_URL 和 MPC_MESSAGE_ROUTER_WS_URL
- mpc-service/.env.example: 更新环境变量文档

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/services/docker-compose.yml

@@ -336,7 +336,9 @@ services:
       - KAFKA_GROUP_ID=mpc-service-group
       # MPC System (deployed on 192.168.1.111)
       - MPC_ACCOUNT_SERVICE_URL=http://192.168.1.111:4000
+      - MPC_COORDINATOR_URL=http://192.168.1.111:8081
       - MPC_SESSION_COORDINATOR_URL=http://192.168.1.111:8081
+      - MPC_MESSAGE_ROUTER_WS_URL=ws://192.168.1.111:8082
       - MPC_SERVER_PARTY_API_URL=http://192.168.1.111:8083
       - MPC_API_KEY=rwa-mpc-api-key-2024-secure-access-token
       - SHARE_MASTER_KEY=${SHARE_MASTER_KEY}

backend/services/mpc-service/.env.example

@@ -29,8 +29,11 @@ KAFKA_GROUP_ID=mpc-party-group
 # MPC System (deployed on 192.168.1.111)
 # account-service: Creates keygen/signing sessions
 MPC_ACCOUNT_SERVICE_URL=http://192.168.1.111:4000
-# session-coordinator: Coordinates TSS sessions
+# session-coordinator: Coordinates TSS sessions (used by MPCCoordinatorClient)
+MPC_COORDINATOR_URL=http://192.168.1.111:8081
 MPC_SESSION_COORDINATOR_URL=http://192.168.1.111:8081
+# message-router: WebSocket for TSS message routing
+MPC_MESSAGE_ROUTER_WS_URL=ws://192.168.1.111:8082
 # server-party-api: Generates user shares (synchronous)
 MPC_SERVER_PARTY_API_URL=http://192.168.1.111:8083
 # API key for authenticating with MPC system