```

refactor: 移除审批和回写功能模块

移除了整个审批(approvals)和官方回写(writebacks)功能模块，
包括相关模型、路由、服务和配置项。更新了数据库迁移文件，
删除了相关的审批请求表和官方回写运行表。同时从API路由器中
移除了相应的路由，并调整了安全常量和字段验证器以匹配变更。
```

app/modules/events/routes.py

@@ -2,6 +2,7 @@ from fastapi import APIRouter, Depends, Query
 from sqlalchemy.orm import Session
 
 from app.core.database import get_db
+from app.core.operation_guard import require_operations_enabled
 from app.core.security import require_api_key
 from app.modules.events.constants import EventResponseKey
 from app.modules.events.service import EventService, _serialize_event
@@ -30,6 +31,7 @@ def dispatch_event(
     event_id: str,
     db: Session = Depends(get_db),
 ) -> dict:
+    require_operations_enabled()
     return {EventResponseKey.EVENT: _serialize_event(EventService(db).dispatch_event(event_id))}
 
 
@@ -38,4 +40,5 @@ def dispatch_pending(
     limit: int = Query(default=100, ge=1, le=500),
     db: Session = Depends(get_db),
 ) -> dict:
+    require_operations_enabled()
     return {EventResponseKey.ITEMS: EventService(db).dispatch_pending(limit=limit)}