修复订单重复推送走兑换逻辑bug, 修复任务关闭失败bug

apps/backend/src/db/migrations/003_message_delivery_dedupe_index.sql

@@ -0,0 +1,3 @@
+CREATE INDEX IF NOT EXISTS idx_message_deliveries_dedupe_success
+ON message_deliveries(provider, platform, shop_id, platform_order_id, channel, claim_url, created_at DESC)
+WHERE status = 'success';