getSessionId method
Returns the current session ID from storage. Falls back to generating one if none exists (e.g. if called before initialize).
Implementation
Future<String> getSessionId() async {
final storage = HiveStorageService.instance;
final existing = await storage.getSessionId();
if (existing != null) return existing;
// Safety fallback — should not happen in normal flow.
final sessionId = const Uuid().v4();
await storage.setSessionId(sessionId);
await storage.setSessionTimestamp(DateTime.now().millisecondsSinceEpoch);
return sessionId;
}