fix(finance): 重写履约路由迁移与统一渠道配置

重写 120/121 迁移，统一内部 SKU、渠道 id、config_json 和旧规则转换。

后台渠道配置改读统一渠道表，卡券与人工配置不再写旧规则。

增加安全渠道切换，并排除已关闭、失败或过期的历史任务载体。

按生产 119 基线重跑迁移、完整履约财务链路和严格预检。

apps/backend/scripts/cleanup-legacy-sku-code-rules.ts

@@ -77,17 +77,6 @@ async function main() {
     converted.push({ id: rule.id, matchKey: rule.match_key, internalSku, channel: rule.channel })
     if (!apply) continue
 
-    await query(
-      `
-        INSERT INTO sku_channel_rules (
-          provider, shop_id, match_key_type, match_key, channel, priority,
-          source, enabled, note, created_at, updated_at
-        ) VALUES ('', '', 'internal_sku', $1, $2, $3, $4, TRUE,
-                  '由旧 sku_code 规则迁移', NOW(), NOW())
-        ON CONFLICT (provider, shop_id, match_key_type, match_key, channel) DO NOTHING
-      `,
-      [internalSku, rule.channel, rule.priority, rule.source || 'operator'],
-    )
     await query(
       `UPDATE internal_sku_channels
        SET is_fallback = TRUE,