迁移合同费用通用附件

1、删除旧费用附件 API、CRUD、模型和专用前端面板，统一改用通用附件能力。

2、调整合同费用接口为 study_id 语义，并补充合同、凭证、发票等附件类型的权限映射。

3、将合同费用新建和编辑改为抽屉流程，详情页与列表页复用同一编辑组件。

4、补充数据库迁移、附件列表、合同费用抽屉和权限场景测试，覆盖旧权限移除与新流程。

backend/app/core/deps.py

@@ -323,9 +323,14 @@ def require_study_not_locked():
     from app.crud import study as study_crud
     from app.crud import faq_category as faq_category_crud
     from app.crud import faq_item as faq_item_crud
+    from app.crud import contract_fee as contract_fee_crud
+    from app.crud import contract_fee_payment as contract_fee_payment_crud
 
     async def resolve_study_id(request: Request, db: AsyncSession) -> uuid.UUID:
-        raw_study_id = request.path_params.get("study_id") or request.query_params.get("study_id")
+        raw_study_id = (
+            request.path_params.get("study_id")
+            or request.query_params.get("study_id")
+        )
         if raw_study_id:
             try:
                 return uuid.UUID(str(raw_study_id))
@@ -376,6 +381,37 @@ def require_study_not_locked():
                 raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="FAQ 不存在")
             return item.study_id
 
+        raw_contract_id = request.path_params.get("contract_id")
+        if raw_contract_id:
+            try:
+                contract_id = uuid.UUID(str(raw_contract_id))
+            except ValueError as exc:
+                raise HTTPException(
+                    status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+                    detail="合同费用 ID 格式错误",
+                ) from exc
+            contract = await contract_fee_crud.get_contract_fee(db, contract_id)
+            if not contract or not contract.study_id:
+                raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="合同费用不存在")
+            return contract.study_id
+
+        raw_payment_id = request.path_params.get("payment_id")
+        if raw_payment_id:
+            try:
+                payment_id = uuid.UUID(str(raw_payment_id))
+            except ValueError as exc:
+                raise HTTPException(
+                    status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+                    detail="分期记录 ID 格式错误",
+                ) from exc
+            payment = await contract_fee_payment_crud.get_payment(db, payment_id)
+            if not payment:
+                raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="分期记录不存在")
+            contract = await contract_fee_crud.get_contract_fee(db, payment.contract_fee_id)
+            if not contract or not contract.study_id:
+                raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="合同费用不存在")
+            return contract.study_id
+
         raise HTTPException(
             status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
             detail="缺少项目 ID",