test(sites): pin first_seen_at of legacy RSS row so ordering test is time-independent (INT-3)

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/server/test/sources-identity/rss-normalize.test.ts

@@ -142,6 +142,8 @@ describe.skipIf(!up)("站点 RSS 条目规范化(HH-2)", () => {
         title: dirty,
         size_bytes: 126353408,
         raw: JSON.stringify({ rss: { link: `${BASE}/details.php?id=219001`, categories: [] } }),
+        // 旧行:固定首见时间,别让"现在"影响下一个用例的发布时间排序(没有 source_published_at 时按首见时间排)
+        first_seen_at: new Date("2026-09-28T00:00:00Z"),
       })
       .returning(["id"])
       .executeTakeFirstOrThrow();