```

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/audit/constants.py

@@ -10,15 +10,10 @@ class AuditAction(StrEnum):
     FEISHU_LONG_CONNECTION_EVENT = "long_connection_event"
     FEISHU_SEND_TEXT = "send_text"
     FEISHU_SEND_CARD = "send_card"
-    APPROVAL_CREATE = "approval.create"
-    APPROVAL_APPROVE = "approval.approve"
-    APPROVAL_REJECT = "approval.reject"
     LEGACY_SYNC_PROJECTS = "sync_projects"
     LEGACY_SYNC_TASKS = "sync_tasks"
     RISK_EVENT_ACTION = "risk_event_action"
     REPORT_PUSH = "report_push"
-    WRITEBACK_CREATE = "writeback.create"
-    WRITEBACK_SUBMIT = "writeback.submit"
 
 
 class AuditRiskLevel(StrEnum):
@@ -32,10 +27,8 @@ class AuditSource(StrEnum):
     OPENCLAW = "openclaw"
     RISK = "risk"
     FEISHU = "feishu"
-    APPROVAL = "approval"
     LEGACY_MYSQL = "legacy_mysql"
     REPORTS = "reports"
-    WRITEBACK = "writeback"
 
 
 class AuditTargetType(StrEnum):