feat(server): /metrics 可观测与日志上下文（F22）

- 新增 Prometheus 指标端点 /metrics（HTTP + DB + 作业统计）
- request.log 绑定 requestId/actorId，避免日志难追踪
- cron/pg-boss 作业增加 metrics 计数（runs/processed）
- 更新 env/runbook/README 与 v3 CSV 状态推进

deploy/trialrun/docker-compose.yml

@@ -30,6 +30,7 @@ services:
         condition: service_healthy
     environment:
       NODE_ENV: production
+      METRICS_ENABLED: ${METRICS_ENABLED}
       APP_ORIGIN: ${APP_ORIGIN}
       JWT_SECRET: ${JWT_SECRET}
       DATABASE_URL: ${DATABASE_URL}
@@ -77,6 +78,7 @@ services:
     command: ["npm", "run", "worker"]
     environment:
       NODE_ENV: production
+      METRICS_ENABLED: ${METRICS_ENABLED}
       APP_ORIGIN: ${APP_ORIGIN}
       JWT_SECRET: ${JWT_SECRET}
       DATABASE_URL: ${DATABASE_URL}
@@ -112,6 +114,7 @@ services:
         condition: service_healthy
     environment:
       NODE_ENV: production
+      METRICS_ENABLED: ${METRICS_ENABLED}
       APP_ORIGIN: ${APP_ORIGIN}
       JWT_SECRET: ${JWT_SECRET}
       DATABASE_URL: ${DATABASE_URL}