speed up series update

lib/core/api/backend_api.dart

@@ -185,6 +185,39 @@ class BackendApi {
     return (map['id'] as num).toInt();
   }
 
+  Future<int> upsertEpisodesBulk(int seasonId, List<Map<String, dynamic>> episodes) async {
+    final map = await _post({
+      'action': 'upsert_episodes_bulk',
+      'season_id': seasonId,
+      'episodes': episodes,
+    });
+    return (map['count'] as num?)?.toInt() ?? 0;
+  }
+
+  Future<Map<int, int>> upsertSeasonsBulk(int showId, List<Map<String, dynamic>> seasons) async {
+    final map = await _post({
+      'action': 'upsert_seasons_bulk',
+      'show_id': showId,
+      'seasons': seasons,
+    });
+    final m = <int,int>{};
+    final any = map['map'];
+    if (any is Map) {
+      for (final e in any.entries) {
+        final k = int.tryParse(e.key.toString());
+        final v = (e.value as num?)?.toInt();
+        if (k != null && v != null) m[k] = v;
+      }
+    }
+    return m;
+  }
+
+  Future<Map<String, dynamic>> getCapabilities() async {
+    final map = await _post({'action': 'get_capabilities'});
+    final caps = map['capabilities'];
+    return caps is Map<String, dynamic> ? caps : (caps as Map).cast<String, dynamic>();
+  }
+
   Future<int?> getShowDbIdByTmdbId(int tmdbId) async {
     final map = await _post({'action': 'get_show_by_tmdb', 'tmdb_id': tmdbId});
     final v = map['id'];