feat(核算)!: 添加 T+ 正式核算与采集托管

补齐源快照、资料预演、正式导入及工资核算的依赖链路。
新增版本化输入、逐段 FIFO、生成锁和结构化当月调整，
并提供默认关闭的周期采集、有限重试及 Windows 托管。

原始客户资料、私有配置及首页改动不纳入本次提交。

BREAKING CHANGE: 升级前需应用新增迁移，并通过
PAYROLL_MAKER_USER_ID 绑定实际工资制作人，否则业务只读。
旧单批次核算默认关闭；历史兼容需显式启用
PAYROLL_ALLOW_LEGACY_CALCULATION。生产启用和真实金额待验收。

backend/app/api/router.py

@@ -18,6 +18,7 @@ from app.api.v1.business import receipts as business_receipts
 from app.api.v1.business import shipments as business_shipments
 from app.api.v1.calc import router as calc_router
 from app.api.v1.dashboard import router as dashboard_router
+from app.api.v1.payroll import router as payroll_router
 from app.api.v1.reports import router as reports_router
 from app.api.v1.settlements import router as settlements_router
 from app.api.v1.system import approvals as system_approvals
@@ -69,6 +70,7 @@ v1_router.include_router(business_router)
 
 # 绩效核算（M3 ④）：/api/v1/calc/*，读登录即可、写限管理员与营销后勤
 v1_router.include_router(calc_router)
+v1_router.include_router(payroll_router)
 # 月度结算（M3 ④）：/api/v1/settlements/*，读登录即可、写限管理员与营销后勤
 v1_router.include_router(settlements_router)
 # 报表统计（M4 ⑤）：/api/v1/reports/*，只读，限管理员/财务/领导