feat(calc): 重算授权留痕与批量核算

- calc_receipt 双模式：recalc_reason 非 None=重算（audit action=重算/
  reason 留痕、作废旧版本行、calc_version 自动递增、CAS 仅首算执行——
  重算状态本就是已核算，误跑 CAS 会误报并发撞车）
- recalc_receipt 薄委托（reason 必填、未核算过 400）；重算授权
  require_roles(admin, finance)，营销后勤不可重算
- batch_calc：逐笔独立事务不开外层 audit（嵌套禁令），逐笔成败清单
  （同业务第二笔回款走 #25 重复分支 ok=True/repeated=True）
- 测试 +5：重算版本对/原因缺失 400/未核算重算 400/越权 403/批量清单
- 修 next_version 空表 max NULL → int(None) TypeError

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

backend/app/api/v1/calc.py

@@ -8,9 +8,10 @@
 from typing import Annotated
 
 from fastapi import APIRouter, Depends, Path, Query
+from pydantic import BaseModel, Field
 
 from app.api.deps import DbSession, RequestMetaDep, require_roles
-from app.core.constants import ROLE_ADMIN, ROLE_MARKETING_OPS
+from app.core.constants import ROLE_ADMIN, ROLE_FINANCE, ROLE_MARKETING_OPS
 from app.core.response import ApiResponse, PageResult, ok
 from app.models import User
 from app.schemas.calc import CalcReceiptOut, LedgerOut, LedgerQuery
@@ -19,6 +20,8 @@ from app.services import calc_service
 router = APIRouter(prefix="/calc", tags=["绩效工资 · 绩效核算"])
 
 _CalcWriter = Annotated[User, Depends(require_roles(ROLE_ADMIN, ROLE_MARKETING_OPS))]
+# 重算是授权动作：管理员/财务（营销后勤不可重算）
+_RecalcUser = Annotated[User, Depends(require_roles(ROLE_ADMIN, ROLE_FINANCE))]
 
 
 @router.get("/ledger", response_model=ApiResponse[PageResult[LedgerOut]], summary="绩效台账")
@@ -55,3 +58,50 @@ def calc_receipt(
         calc_service.calc_receipt(session, receipt_id, operator=current_user, meta=meta),
         message="核算完成",
     )
+
+
+class RecalcIn(BaseModel):
+    """重算入参：原因必填（重算授权留痕）。"""
+
+    reason: str = Field(min_length=1, max_length=255, description="重算原因")
+
+
+class BatchIn(BaseModel):
+    """批量核算入参。"""
+
+    receipt_ids: list[int] = Field(min_length=1, description="回款 ID 列表")
+
+
+@router.post(
+    "/receipts/{receipt_id}/recalc",
+    response_model=ApiResponse[CalcReceiptOut],
+    summary="重算回款",
+)
+def recalc_receipt(
+    receipt_id: Annotated[int, Path(ge=1)],
+    payload: RecalcIn,
+    session: DbSession,
+    current_user: _RecalcUser,
+    meta: RequestMetaDep,
+) -> ApiResponse[CalcReceiptOut]:
+    """重算（管理员/财务）：作废旧版本、按当前参数落新版本并留痕。"""
+    return ok(
+        calc_service.recalc_receipt(
+            session, receipt_id, payload.reason, operator=current_user, meta=meta
+        ),
+        message="重算完成",
+    )
+
+
+@router.post("/batch", response_model=ApiResponse[list[dict]], summary="批量核算")
+def batch_calc(
+    payload: BatchIn,
+    session: DbSession,
+    current_user: _CalcWriter,
+    meta: RequestMetaDep,
+) -> ApiResponse[list[dict]]:
+    """批量核算：逐笔独立事务，返回逐笔成败清单（失败不中断其它笔）。"""
+    return ok(
+        calc_service.batch_calc(session, payload.receipt_ids, operator=current_user, meta=meta),
+        message="批量核算完成",
+    )