feat(contacts): обмен контактами NFC→BLE

lib/core/nfc/nfc_exchange_service.dart

@@ -3,13 +3,14 @@ import 'dart:io';
 
 import 'package:flutter/services.dart';
 
-enum NfcEventType { received, cancelled }
+enum NfcEventType { received, cancelled, error }
 
 class NfcEvent {
   final NfcEventType type;
   final int? id;
+  final String? reason;
 
-  const NfcEvent(this.type, this.id);
+  const NfcEvent(this.type, this.id, {this.reason});
 }
 
 class NfcStatus {
@@ -59,9 +60,14 @@ class NfcExchangeService {
   NfcEvent _decodeEvent(dynamic raw) {
     final map = raw is Map ? raw : const {};
     final id = map['id'];
-    final type = map['event'] == 'received'
-        ? NfcEventType.received
-        : NfcEventType.cancelled;
-    return NfcEvent(type, id is int ? id : (id is num ? id.toInt() : null));
+    final parsedId = id is int ? id : (id is num ? id.toInt() : null);
+    switch (map['event']) {
+      case 'received':
+        return NfcEvent(NfcEventType.received, parsedId);
+      case 'error':
+        return NfcEvent(NfcEventType.error, null, reason: map['reason'] as String?);
+      default:
+        return const NfcEvent(NfcEventType.cancelled, null);
+    }
   }
 }