fix(mobile): stabilize relay retry lifecycle

Avoid duplicate disconnect callbacks during authentication and invalidate deliberate reconnect callbacks before replacing the socket.

Co-authored-by: npub1ux8n2yfs8qfvgd75s7kyhar2mztac355v6vmrz4juc9l3msw4pgstums9e <e18f3511303812c437d487ac4bf46ad897dc46946699b18ab2e60bf8ee0ea851@sprout-oss.stage.blox.sqprod.co>
Signed-off-by: npub1ux8n2yfs8qfvgd75s7kyhar2mztac355v6vmrz4juc9l3msw4pgstums9e <e18f3511303812c437d487ac4bf46ad897dc46946699b18ab2e60bf8ee0ea851@sprout-oss.stage.blox.sqprod.co>

mobile/lib/shared/relay/relay_session.dart

@@ -317,6 +317,7 @@ class RelaySessionNotifier extends Notifier<SessionState> {
   /// Force a reconnect (e.g., returning from background).
   Future<void> reconnect() async {
     _reconnectTimer?.cancel();
+    ++_connectionGeneration;
     await _socket?.disconnect();
     _resetReconnectBudget();
     final config = ref.read(relayConfigProvider);

mobile/lib/shared/relay/relay_socket.dart

@@ -102,14 +102,18 @@ class RelaySocket {
     _subscription = _channel!.stream.listen(
       _handleRawMessage,
       onError: (Object error) {
+        final awaitingAuth =
+            _authCompleter != null && !_authCompleter!.isCompleted;
         _failAuth(error);
         _resetConnection();
-        _onDisconnected(error);
+        if (!awaitingAuth) _onDisconnected(error);
       },
       onDone: () {
+        final awaitingAuth =
+            _authCompleter != null && !_authCompleter!.isCompleted;
         _failAuth(null);
         _resetConnection();
-        _onDisconnected(null);
+        if (!awaitingAuth) _onDisconnected(null);
       },
     );