fix(distribution): 修正商品归属回填、禁止全站灌货并拒绝无效站点头

用货架写入时间与上传来源回滚误标产地，不再依赖绝对时间戳；同步仅收本站上传与显式勾选。

backend/internal/modules/distribution/handler.go

@@ -237,6 +237,13 @@ func (h *Handler) SyncSiteAccounts(c *gin.Context) {
 			siteID = uint64(qID)
 		}
 	}
+	var req SyncSiteAccountsRequest
+	if c.Request.ContentLength != 0 {
+		if err := c.ShouldBindJSON(&req); err != nil {
+			response.BadRequest(c, "同步参数不正确")
+			return
+		}
+	}
 	adminID, _ := currentAdminID(c)
 	scoped, err := h.service.ScopeSiteID(c.Request.Context(), adminID, siteID)
 	if err != nil {
@@ -247,7 +254,7 @@ func (h *Handler) SyncSiteAccounts(c *gin.Context) {
 		response.BadRequest(c, "site_id 不正确")
 		return
 	}
-	result, err := h.service.SyncSiteAccounts(c.Request.Context(), adminID, scoped)
+	result, err := h.service.SyncSiteAccounts(c.Request.Context(), adminID, scoped, req.ListingIDs)
 	if err != nil {
 		writeError(c, err)
 		return
@@ -741,6 +748,10 @@ func writeError(c *gin.Context, err error) {
 		response.Error(c, http.StatusForbidden, "admin_disabled", "分销管理员账号已被禁用")
 	case errors.Is(err, ErrInvalidAmount), errors.Is(err, ErrInvalidRate), errors.Is(err, ErrInvalidServiceUnit), errors.Is(err, ErrUnsupportedMode), errors.Is(err, ErrInvalidOrderKind), errors.Is(err, ErrInvalidPeriod), errors.Is(err, ErrBatchAlreadySettled), errors.Is(err, ErrSettlementBatchEmpty), errors.Is(err, ErrSettlementTotalMismatch):
 		response.BadRequest(c, "分销规则参数不正确")
+	case errors.Is(err, ErrTooManySyncListings):
+		response.BadRequest(c, "一次勾选同步的商品过多")
+	case errors.Is(err, ErrSyncListingNotFound):
+		response.BadRequest(c, "勾选的商品不存在")
 	case errors.Is(err, ErrLiveMoneyMovementFrozen):
 		response.Error(c, http.StatusForbidden, "settlement_frozen", "分销结算与提现已冻结，待分成口径确认后再开放")
 	case errors.Is(err, ErrSiteAccessDenied):