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/migrations/000076_fix_listing_attribution_without_timestamp.sql

@@ -0,0 +1,71 @@
+-- +goose Up
+
+-- 补偿 000072 / 000073：货架展示不等于产地，禁止用绝对时间回滚。
+-- 本站上传特征：无 listing_uploads（外部导入走该表，source_channel=咸鱼/淘宝等），
+-- 且 distribution_site_accounts 与商品在同一发布事务内写入（created_at 相差不超过 5 秒）。
+
+SET @sql = IF(
+  (SELECT COUNT(*) FROM information_schema.COLUMNS WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'rental_listings' AND COLUMN_NAME = 'source_channel') = 0,
+  'ALTER TABLE rental_listings ADD COLUMN source_channel VARCHAR(64) NOT NULL DEFAULT '''' AFTER distribution_site_id',
+  'SELECT 1'
+);
+PREPARE stmt FROM @sql;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+
+-- 1. 恢复被 000073 时间戳误清空的本站上传归属
+UPDATE rental_listings l
+INNER JOIN (
+  SELECT dsa.listing_id, MIN(dsa.site_id) AS site_id
+  FROM distribution_site_accounts dsa
+  INNER JOIN rental_listings l2 ON l2.id = dsa.listing_id
+  LEFT JOIN listing_uploads lu ON lu.listing_id = dsa.listing_id
+  WHERE lu.id IS NULL
+    AND TIMESTAMPDIFF(SECOND, l2.created_at, dsa.created_at) BETWEEN 0 AND 5
+  GROUP BY dsa.listing_id
+) origin ON origin.listing_id = l.id
+SET l.distribution_site_id = origin.site_id
+WHERE l.distribution_site_id IS NULL OR l.distribution_site_id = 0;
+
+-- 2. 清掉仅因货架回填产生的归属（外部导入，或 DSA 明显晚于商品创建）
+UPDATE rental_listings l
+LEFT JOIN listing_uploads lu ON lu.listing_id = l.id
+LEFT JOIN distribution_site_accounts origin_dsa
+  ON origin_dsa.listing_id = l.id
+ AND origin_dsa.site_id = l.distribution_site_id
+ AND TIMESTAMPDIFF(SECOND, l.created_at, origin_dsa.created_at) BETWEEN 0 AND 5
+SET l.distribution_site_id = NULL
+WHERE l.distribution_site_id IS NOT NULL
+  AND l.distribution_site_id <> 0
+  AND (lu.id IS NOT NULL OR origin_dsa.id IS NULL);
+
+-- 3. 回填来源渠道快照：分销站用 site_code，外部导入用 listing_uploads.source_channel
+UPDATE rental_listings l
+INNER JOIN distribution_sites s ON s.id = l.distribution_site_id
+SET l.source_channel = s.site_code
+WHERE l.distribution_site_id IS NOT NULL
+  AND l.distribution_site_id <> 0
+  AND l.source_channel = '';
+
+UPDATE rental_listings l
+INNER JOIN (
+  SELECT lu.listing_id, MAX(NULLIF(lu.source_channel, '')) AS source_channel
+  FROM listing_uploads lu
+  WHERE lu.listing_id IS NOT NULL
+  GROUP BY lu.listing_id
+) upload ON upload.listing_id = l.id
+SET l.source_channel = COALESCE(upload.source_channel, '')
+WHERE (l.distribution_site_id IS NULL OR l.distribution_site_id = 0)
+  AND l.source_channel = ''
+  AND COALESCE(upload.source_channel, '') <> '';
+
+-- +goose Down
+
+SET @sql = IF(
+  (SELECT COUNT(*) FROM information_schema.COLUMNS WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'rental_listings' AND COLUMN_NAME = 'source_channel') > 0,
+  'ALTER TABLE rental_listings DROP COLUMN source_channel',
+  'SELECT 1'
+);
+PREPARE stmt FROM @sql;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;