fix(cost-center): 禁止追溯改价，改价只能当前或未来生效

- 后端统一校验：retroactive 请求直接拒绝，effectiveFrom 早于当前时间拒绝
- 去掉「追溯至历史订单」入口，改价只影响之后的新订单
- 历史订单成本与成交价由快照固化，不再受改价影响

apps/frontend/src/services/admin/cost-center.ts

@@ -145,7 +145,6 @@ export function setAdminAffiliateProductPrice(
   payload: {
     amountFen: number
     effectiveFrom?: string
-    retroactive?: boolean
     changeReason?: string
   },
 ) {
@@ -486,7 +485,6 @@ export function setAdminProductPrice(
   payload: {
     amountFen: number
     effectiveFrom?: string
-    retroactive?: boolean
     changeReason?: string
     syncOpenOrders?: boolean
   },