fix: какое то уведомление при входе в незнакомые каналы

lib/backend/api.dart

@@ -266,7 +266,11 @@ class Api {
   }
 
   /// Отправляет запрос и ждёт ответ от сервера.
-  Future<Packet> sendRequest(int opcode, Map<dynamic, dynamic> payload) async {
+  Future<Packet> sendRequest(
+    int opcode,
+    Map<dynamic, dynamic> payload, {
+    bool silent = false,
+  }) async {
     final session = _session;
     if (session == null) {
       throw StateError('Нет соединения (${Opcode.name(opcode)})');
@@ -296,7 +300,7 @@ class Api {
         throw ex;
       }
       final text = _serverErrorText(packet.payload);
-      if (text != null) _errorController.add(text);
+      if (text != null && !silent) _errorController.add(text);
       final err = PacketError(
         messageFromErrorPayload(packet.payload),
         errorKey: resp.errorKey,

lib/backend/modules/chats.dart

@@ -399,7 +399,7 @@ class ChatsModule {
           'chatId': chatId,
           'messageId': msgIdNum,
           'mark': mark,
-        });
+        }, silent: true);
       } catch (_) {}
     }
 
@@ -424,7 +424,7 @@ class ChatsModule {
           'chatId': chatId,
           'messageId': msgIdNum,
           'mark': mark,
-        });
+        }, silent: true);
       } catch (_) {}
     }
 
@@ -1348,12 +1348,36 @@ class ChatsModule {
       await api.sendRequest(Opcode.chatSubscribe, {
         'chatId': chatId,
         'subscribe': subscribe,
-      });
+      }, silent: true);
     } catch (e) {
       logger.w('subscribeChat failed: $e');
     }
   }
 
+  Future<({CachedChat chat, int? subscribersCount})> joinChannel(
+    Api api,
+    String link,
+    int accountId,
+  ) async {
+    final packet = await api.sendRequest(Opcode.chatJoin, {
+      'link': link,
+    }, silent: true);
+    if (!packet.isOk) {
+      throw PacketError(messageFromErrorPayload(packet.payload));
+    }
+    final payload = packet.payload;
+    final chatMap = payload is Map ? payload['chat'] : null;
+    if (chatMap is! Map) {
+      throw const PacketError('Не удалось подписаться');
+    }
+    final cached = await cacheServerChat(chatMap, accountId);
+    if (cached == null) {
+      throw const PacketError('Не удалось подписаться');
+    }
+    final count = chatMap['participantsCount'];
+    return (chat: cached, subscribersCount: count is int ? count : null);
+  }
+
   Future<bool> ensureChatCached(Api api, int accountId, int chatId) async {
     final rows = await AppDatabase.loadChat(accountId, chatId);
     if (rows.isNotEmpty) return true;