```

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/dashboard/service.py

@@ -3,8 +3,6 @@ from typing import Any
 from sqlalchemy import func, select
 from sqlalchemy.orm import Session
 
-from app.modules.approvals.constants import ApprovalStatus
-from app.modules.approvals.models import ApprovalRequest
 from app.modules.audit.models import AuditLog
 from app.modules.business.constants import DONE_STATUSES, PROJECT_CLOSED_STATUSES, StatusValue
 from app.modules.business.models import (
@@ -22,8 +20,6 @@ from app.modules.reports.constants import ReportPushStatus
 from app.modules.risk.service import RiskService
 from app.modules.workflows.constants import WorkflowStatus
 from app.modules.workflows.models import WorkflowInstance
-from app.modules.writebacks.constants import WritebackStatus
-from app.modules.writebacks.models import OfficialWritebackRun
 
 
 class DashboardService:
@@ -36,10 +32,6 @@ class DashboardService:
     def summary(self) -> dict[str, Any]:
         active_projects = self._count(Project, Project.status.notin_(PROJECT_CLOSED_STATUSES))
         open_tasks = self._count(WorkTask, WorkTask.status.notin_(DONE_STATUSES))
-        pending_approvals = self._count(
-            ApprovalRequest,
-            ApprovalRequest.status == ApprovalStatus.PENDING,
-        )
         open_risk_events = self._count(RiskEvent, RiskEvent.status == StatusValue.OPEN)
         unassigned_open_risks = self._count(
             RiskEvent,
@@ -57,14 +49,6 @@ class DashboardService:
             WorkflowInstance,
             WorkflowInstance.status == WorkflowStatus.FAILED,
         )
-        disabled_writebacks = self._count(
-            OfficialWritebackRun,
-            OfficialWritebackRun.status == WritebackStatus.DISABLED,
-        )
-        failed_writebacks = self._count(
-            OfficialWritebackRun,
-            OfficialWritebackRun.status == WritebackStatus.FAILED,
-        )
         latest_reports = self.db.execute(
             select(WorkReport).order_by(WorkReport.id.desc()).limit(5)
         ).scalars()
@@ -82,7 +66,6 @@ class DashboardService:
             "metrics": {
                 "active_projects": active_projects,
                 "open_tasks": open_tasks,
-                "pending_approvals": pending_approvals,
                 "open_risk_events": open_risk_events,
                 "unassigned_open_risks": unassigned_open_risks,
                 "failed_push_runs": failed_push_runs,
@@ -90,8 +73,6 @@ class DashboardService:
                 "failed_events": failed_events,
                 "running_workflows": running_workflows,
                 "failed_workflows": failed_workflows,
-                "disabled_writebacks": disabled_writebacks,
-                "failed_writebacks": failed_writebacks,
                 "risk_level": risk_summary["risk_level"],
                 "risk_score": float(risk_summary["risk_score"]),
             },