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/crud/contract_fee.py

@@ -16,7 +16,7 @@ async def create_contract_fee(
     contract_in: ContractFeeCreate,
 ) -> ContractFee:
     contract = ContractFee(
-        project_id=contract_in.project_id,
+        project_id=contract_in.study_id,
         center_id=contract_in.center_id,
         contract_no=contract_in.contract_no,
         signed_date=contract_in.signed_date,
@@ -39,18 +39,18 @@ async def get_contract_fee(db: AsyncSession, contract_id: uuid.UUID) -> Contract
     return result.scalar_one_or_none()
 
 
-async def get_contract_fee_by_project_center(
-    db: AsyncSession, project_id: uuid.UUID, center_id: uuid.UUID
+async def get_contract_fee_by_study_center(
+    db: AsyncSession, study_id: uuid.UUID, center_id: uuid.UUID
 ) -> ContractFee | None:
     result = await db.execute(
-        select(ContractFee).where(ContractFee.project_id == project_id, ContractFee.center_id == center_id)
+        select(ContractFee).where(ContractFee.project_id == study_id, ContractFee.center_id == center_id)
     )
     return result.scalar_one_or_none()
 
 
 async def list_contract_fees(
     db: AsyncSession,
-    project_id: uuid.UUID,
+    study_id: uuid.UUID,
     center_id: uuid.UUID | None = None,
     center_ids: set[uuid.UUID] | None = None,
     q: str | None = None,
@@ -81,7 +81,7 @@ async def list_contract_fees(
         )
         .join(Site, Site.id == ContractFee.center_id)
         .outerjoin(ContractFeePayment, ContractFeePayment.contract_fee_id == ContractFee.id)
-        .where(ContractFee.project_id == project_id)
+        .where(ContractFee.project_id == study_id)
         .group_by(ContractFee.id, Site.name)
     )