fix(catalog): scan air_timezone in paginated item queries

scanItemsWithTotal was not updated for the new air_timezone column, yet the
shared column lists it reads (itemColumns, qualifiedListItemColumns) include
it. Search and BrowseFavorites build their SELECTs from those lists with
COUNT(*) OVER (), so each row carried one more column than the scan had
destinations and every call failed at scan time with a pgx mismatch. Add the
missing &item.AirTimezone target between AirTime and ShowStatus.

Found during PR #21 review (critical: Search/Favorites runtime regression).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/catalog/item_repo.go

@@ -277,6 +277,7 @@ func scanItemsWithTotal(rows pgx.Rows) ([]*models.MediaItem, int, error) {
 			&item.FirstAirDate,
 			&item.LastAirDate,
 			&item.AirTime,
+			&item.AirTimezone,
 			&item.ShowStatus,
 			&item.MatchedAt,
 			&item.LastRefreshed,