```

feat: 添加数据库迁移脚本并更新Dockerfile配置

- 在Dockerfile中添加alembic配置文件和目录的复制指令
- 更新alembic/env.py注册新的模块模型：events、workflows、writebacks
- 生成完整的初始数据库schema迁移脚本，包含以下表：
  - approval_requests, attendance_records, audit_logs, domain_events
  - expenses, feishu_event_receipts, fund_accounts, legacy_sync_runs
  - official_writeback_runs, performance_metrics, policies, procurements
  - projects, report_push_runs, risk_event_actions, risk_events
  - standards, suppliers, work_reports, work_tasks, workflow_actions
  - workflow_instances等21个数据表结构定义
- 在API路由器中添加新模块的路由：events、workflows、writebacks、observability
```

app/core/request_context.py

@@ -0,0 +1,16 @@
+from contextvars import ContextVar, Token
+
+
+_request_id: ContextVar[str | None] = ContextVar("request_id", default=None)
+
+
+def set_request_id(request_id: str) -> Token:
+    return _request_id.set(request_id)
+
+
+def reset_request_id(token: Token) -> None:
+    _request_id.reset(token)
+
+
+def get_request_id() -> str | None:
+    return _request_id.get()