persist method
Persists current in-memory queue to storage.
Implementation
Future<void> persist() async {
if (storage == null) return;
try {
final list = _queue.map((m) => m.toMap()).toList();
await storage!.write(_storageKey, jsonEncode(list));
} catch (e) {
logger.error('OfflineMutationQueue: Failed to persist mutations to storage: $e');
}
}