Poster search through a posters table and releases_poster_newest_idx; complete releases are final; the tail before everything (-3)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/services/batch_store.ts

@@ -243,6 +243,9 @@ class BatchStore {
           taken.set(r.key, n)
           return { release_key: n === 1 ? r.key : `${r.key}:${n}`, key: r.key, upload: r.upload, ...row(r) }
         }
+        // Their posters, for poster search (posters: one row per poster, searched by trigram; migration 4000).
+        const posters = [...new Set(fresh.map((r) => r.poster).filter((p): p is string => !!p))]
+        if (posters.length > 0) await trx.rawQuery(`INSERT INTO posters (poster) SELECT DISTINCT left(p, 200) FROM unnest(?::text[]) AS p ON CONFLICT DO NOTHING`, [posters])
         let inserts = fresh.map(numbered)
         // Writers of other groups number the same key at the same time (a spam post crossposted to 67
         // groups; only the group is locked): a number taken meanwhile is skipped, and the next one tried.