perf(database): skip the per-launch duplicate scan and keep playlist payloads last (#1883)

deduplicateXtreamCache no longer scans the whole catalog on every launch once both unique indexes exist (7.8 s cold on a 3.9M-title library). The playlists table keeps payload as its last column (playlists-table.ts); ensurePlaylistsPayloadLast rebuilds an existing table once, keeping its indexes and triggers, foreign keys off, committing only if references referencing playlists gain no violations. On a full copy of that profile initDatabase went from 5.2-8.1 s to 39 ms and the playlist metadata read from 1.5-2 s to 22-34 ms; the one-time rebuild costs about 4 s.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libs/shared/database/src/lib/schema.ts

@@ -52,8 +52,9 @@ export const playlists = sqliteTable('playlists', {
     position: integer('position'),
     favorites: text('favorites'),
     recentlyViewed: text('recently_viewed'),
-    payload: text('payload'),
     lastUsage: text('last_usage'),
+    // Last on purpose: see PLAYLISTS_COLUMNS in connection.ts.
+    payload: text('payload'),
 });
 
 // App key-value state table (e.g. one-time migration flags)