feat: 增加差旅报销标准测算和财务终审流程

新增差旅报销测算接口及 Spreadsheet 规则解析，审批流程拆分
直属领导审批与财务终审两阶段并细分权限，修复 PDF 文本层
缺失时自动回退 OCR，提交后清理关联会话，前端适配审批流
交互并补充单元测试。

server/src/app/api/v1/endpoints/reimbursements.py

@@ -20,9 +20,12 @@ from app.schemas.reimbursement import (
     ExpenseClaimReturnPayload,
     ReimbursementCreate,
     ReimbursementRead,
+    TravelReimbursementCalculatorRequest,
+    TravelReimbursementCalculatorResponse,
 )
 from app.services.expense_claims import ExpenseClaimService
 from app.services.reimbursement import ReimbursementService
+from app.services.travel_reimbursement_calculator import TravelReimbursementCalculatorService
 
 router = APIRouter()
 DbSession = Annotated[Session, Depends(get_db)]
@@ -50,6 +53,29 @@ def create_reimbursement(payload: ReimbursementCreate, db: DbSession) -> Reimbur
     return ReimbursementService(db).create_reimbursement(payload)
 
 
+@router.post(
+    "/travel-calculator",
+    response_model=TravelReimbursementCalculatorResponse,
+    summary="差旅报销标准测算",
+    description="根据规则中心的差旅报销表、当前员工职级、出差天数与地点测算住宿和补贴参考金额。",
+    responses={
+        status.HTTP_400_BAD_REQUEST: {
+            "model": ErrorResponse,
+            "description": "测算入参或规则匹配失败。",
+        }
+    },
+)
+def calculate_travel_reimbursement(
+    payload: TravelReimbursementCalculatorRequest,
+    db: DbSession,
+    current_user: CurrentUser,
+) -> TravelReimbursementCalculatorResponse:
+    try:
+        return TravelReimbursementCalculatorService(db).calculate(payload, current_user)
+    except ValueError as error:
+        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(error)) from error
+
+
 @router.get(
     "/claims",
     response_model=list[ExpenseClaimRead],
@@ -463,8 +489,8 @@ def return_expense_claim(
 @router.post(
     "/claims/{claim_id}/approve",
     response_model=ExpenseClaimRead,
-    summary="直属领导审批通过报销单",
-    description="当前审批人确认报销信息无误后，将报销单从直属领导审批流转到财务审批。",
+    summary="审批通过报销单",
+    description="直属领导审批通过后流转到财务审批；财务终审通过后进入归档入账。",
     responses={
         status.HTTP_404_NOT_FOUND: {
             "model": ErrorResponse,
@@ -497,7 +523,7 @@ def approve_expense_claim(
     "/claims/{claim_id}",
     response_model=ExpenseClaimActionResponse,
     summary="删除报销单",
-    description="普通用户仅可删除草稿或待补充报销单；财务人员和高级管理人员可删除可见报销单。",
+    description="申请人仅可删除自己的草稿、待补充或退回单据；高级管理人员可删除可见单据，财务人员没有删除权限。",
     responses={
         status.HTTP_404_NOT_FOUND: {
             "model": ErrorResponse,