feat(media-supply): resource cache sync and order flow refinements

Add a resource cache sync entrypoint (RunMediaResourceSyncOnce) driven
by the new scheduler job, and rework the backlink/sync worker around it.
Tune the meijiequan client and slow the default backlink sync interval
from 10m to 30m to reduce upstream pressure.

Trim unused public/transport surface (handler + router + swagger) and
simplify admin-web order management and ops-web media-supply views,
dropping stale shared-types fields.

server/internal/tenant/app/media_supply_public.go

@@ -45,7 +45,7 @@ func mediaSupplyPublicErrorMessage(err error) string {
 	case errors.Is(err, errMeijiequanOrderRejected):
 		return "媒体供应商拒绝投稿，请检查文章内容或联系管理员处理"
 	case errors.Is(err, errMediaSupplySelectedResourcesMissing):
-		return "媒体资源价格刷新失败，请稍后重试或重新选择媒体"
+		return "媒体资源暂不可用或已下架，请重新选择媒体"
 	case errors.Is(err, errMediaSupplyLockedSellBelowCost):
 		return "媒体成本价已变化，当前锁定价格低于成本，请重新提交"
 	case errors.Is(err, errMediaSupplyAccountUserIDMissing):
@@ -63,7 +63,7 @@ func mediaSupplyPublicGenericErrorMessage(message string) string {
 	lower := strings.ToLower(message)
 	switch {
 	case strings.Contains(lower, "failed to refresh supplier price"):
-		return "媒体资源价格刷新失败，请稍后重试或重新选择媒体"
+		return "媒体资源暂不可用或已下架，请重新选择媒体"
 	case strings.Contains(lower, "supplier cost increased above locked sell price"):
 		return "媒体成本价已变化，当前锁定价格低于成本，请重新提交"
 	case strings.Contains(lower, "username") || strings.Contains(lower, "password") || strings.Contains(lower, "credentials"):