权限系统迁移完成：接口级权限 + 前置权限检查

## 核心改进
- 完全迁移到接口级权限（68个API端点）
- 实现前置权限检查机制，解决跨模块数据访问权限问题
- 添加权限管理API端点，支持前置权限查询

## 关键变更
1. 权限配置系统
   - 添加OPERATION_PREREQUISITES映射表
   - 所有操作配置前置权限依赖

2. 权限检查函数
   - role_has_api_permission()支持前置权限检查
   - get_missing_prerequisites()获取缺失权限列表

3. 权限管理API
   - GET /api-permissions/operations - 获取所有操作及前置权限
   - GET /api-permissions/operations/prerequisites - 获取前置权限依赖
   - GET /api-permissions/{endpoint_key}/prerequisites - 检查缺失权限

4. API端点迁移
   - 第1批：subjects, visits, aes, monitoring_visit_issues (23个)
   - 第2批：members, sites, project_milestones (11个)
   - 第3批：finance_contracts, fees_contracts, drug_shipments (15个)
   - 第4批：startup endpoints (19个)

## 测试验证
- 单元测试：24个测试全部通过
- 集成测试：22个迁移端点测试通过
- 前置权限测试：12个测试全部通过
- 总计：46个测试全部通过

## 向后兼容性
- 模块级权限表保留用于历史数据
- 接口级权限未配置时自动回退到模块级权限
- 现有权限配置继续有效

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

backend/app/api/v1/fees_contracts.py

@@ -85,7 +85,7 @@ async def list_contract_fees(
     db: AsyncSession = Depends(get_db_session),
     current_user=Depends(get_current_user),
 ) -> FeeApiResponse[list[ContractFeeListItem]]:
-    await _ensure_project_access(db, project_id, current_user, "GET:/fees/contracts")
+    await _ensure_project_access(db, project_id, current_user, "fees_contracts:read")
     cra_scope = await get_cra_site_scope(db, project_id, current_user)
     center_ids = cra_scope[0] if cra_scope else None
     if center_id and center_ids is not None and center_id not in center_ids:
@@ -141,7 +141,7 @@ async def get_contract_fee(
     contract = await contract_fee_crud.get_contract_fee(db, contract_id)
     if not contract:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="合同费用不存在")
-    await _ensure_project_access(db, contract.project_id, current_user, "GET:/fees/contracts/{id}")
+    await _ensure_project_access(db, contract.project_id, current_user, "fees_contracts:read")
     cra_scope = await get_cra_site_scope(db, contract.project_id, current_user)
     if cra_scope and contract.center_id not in cra_scope[0]:
         raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="权限不足")
@@ -216,7 +216,7 @@ async def create_contract_fee(
     db: AsyncSession = Depends(get_db_session),
     current_user=Depends(get_current_user),
 ) -> FeeApiResponse[ContractFeeRead]:
-    await _ensure_project_access(db, contract_in.project_id, current_user, "POST:/fees/contracts")
+    await _ensure_project_access(db, contract_in.project_id, current_user, "fees_contracts:create")
     existing = await contract_fee_crud.get_contract_fee_by_project_center(
         db, contract_in.project_id, contract_in.center_id
     )
@@ -255,7 +255,7 @@ async def update_contract_fee(
     contract = await contract_fee_crud.get_contract_fee(db, contract_id)
     if not contract:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="合同费用不存在")
-    await _ensure_project_access(db, contract.project_id, current_user, "PATCH:/fees/contracts/{id}")
+    await _ensure_project_access(db, contract.project_id, current_user, "fees_contracts:update")
     await _ensure_center_active(db, contract.project_id, contract.center_id)
     contract = await contract_fee_crud.update_contract_fee(db, contract, contract_in)
     await audit_crud.log_action(
@@ -284,7 +284,7 @@ async def delete_contract_fee(
     contract = await contract_fee_crud.get_contract_fee(db, contract_id)
     if not contract:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="合同费用不存在")
-    await _ensure_project_access(db, contract.project_id, current_user, "DELETE:/fees/contracts/{id}")
+    await _ensure_project_access(db, contract.project_id, current_user, "fees_contracts:delete")
     await _ensure_center_active(db, contract.project_id, contract.center_id)
     await contract_fee_crud.delete_contract_fee(db, contract)
     await audit_crud.log_action(