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/visits.py

@@ -3,7 +3,7 @@ import uuid
 from fastapi import APIRouter, Depends, HTTPException, status
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.core.deps import get_current_user, get_db_session, require_study_not_locked, require_study_permission
+from app.core.deps import get_current_user, get_db_session, require_study_not_locked, require_api_permission
 from app.crud import audit as audit_crud
 from app.crud import site as site_crud
 from app.crud import subject as subject_crud
@@ -33,7 +33,7 @@ async def _ensure_subject_active(db: AsyncSession, subject) -> None:
 @router.get(
     "/",
     response_model=list[VisitRead],
-    dependencies=[Depends(require_study_permission("subjects", "read"))],
+    dependencies=[Depends(require_api_permission("visits:read"))],
 )
 async def list_visits(
     study_id: uuid.UUID,
@@ -50,7 +50,7 @@ async def list_visits(
     "/",
     response_model=VisitRead,
     status_code=status.HTTP_201_CREATED,
-    dependencies=[Depends(require_study_permission("subjects", "write")), Depends(require_study_not_locked())],
+    dependencies=[Depends(require_api_permission("visits:create")), Depends(require_study_not_locked())],
 )
 async def create_visit(
     study_id: uuid.UUID,
@@ -115,7 +115,7 @@ async def create_visit(
     "/early-termination",
     response_model=VisitRead,
     status_code=status.HTTP_201_CREATED,
-    dependencies=[Depends(require_study_permission("subjects", "write")), Depends(require_study_not_locked())],
+    dependencies=[Depends(require_api_permission("visits:create")), Depends(require_study_not_locked())],
 )
 async def create_early_termination(
     study_id: uuid.UUID,
@@ -168,7 +168,7 @@ async def create_early_termination(
 @router.patch(
     "/{visit_id}",
     response_model=VisitRead,
-    dependencies=[Depends(require_study_permission("subjects", "write")), Depends(require_study_not_locked())],
+    dependencies=[Depends(require_api_permission("visits:update")), Depends(require_study_not_locked())],
 )
 async def update_visit(
     study_id: uuid.UUID,
@@ -211,7 +211,7 @@ async def update_visit(
 @router.delete(
     "/{visit_id}",
     status_code=status.HTTP_204_NO_CONTENT,
-    dependencies=[Depends(require_study_permission("subjects", "write")), Depends(require_study_not_locked())],
+    dependencies=[Depends(require_api_permission("visits:delete")), Depends(require_study_not_locked())],
 )
 async def delete_visit(
     study_id: uuid.UUID,