feat(auth): include subscription tier in token and session payload

- Adds subscription tier info to access/refresh tokens.
- Stores tier details in session Redis record.
- Returns tier data in login/register response.
- Uses default tier when user has none.

lib/db/migrations/run-migrations.ts

@@ -38,6 +38,7 @@ const MIGRATIONS = [
   "016_create_unified_items_table.sql",
   "017_add_items_foreign_key.sql",
   "018_migrate_listings_to_unified_items.sql",
+  "019_subscription_tiers.sql",
 ];
 
 async function runMigrations() {