fix(settings): pass the connection dialect when listing known servers in discovery

PR #1666 merged without compiling: it maps existing connections into the
add-server discovered list, but DiscoveredJellyfinServer gained a required
dialect with the Emby backend. Carry the connection's dialect through and
list only connections matching the screen's dialect, so the Add Emby screen
does not offer existing Jellyfin servers.

lib/screens/settings/add_jellyfin_screen.dart

@@ -158,15 +158,23 @@ class _AddJellyfinScreenState extends State<AddJellyfinScreen> with AsyncFormSta
   Future<void> _discoverLocalServers() async {
     final attemptId = ++_localDiscoveryAttemptId;
     try {
-       List<Connection> existingConnections = const <Connection>[];
-       try {
-         existingConnections = await context.read<ConnectionRegistry>().list();
-       } on ProviderNotFoundException {
-         // No ConnectionRegistry in the tree (tests / isolated subtrees).
-       }
-       final existing = existingConnections
+      List<Connection> existingConnections = const <Connection>[];
+      try {
+        existingConnections = await context.read<ConnectionRegistry>().list();
+      } on ProviderNotFoundException {
+        // No ConnectionRegistry in the tree (tests / isolated subtrees).
+      }
+      final existing = existingConnections
           .whereType<JellyfinConnection>()
-          .map((c) => DiscoveredJellyfinServer(address: c.baseUrl, id: c.serverMachineId, name: c.serverName));
+          .where((c) => c.dialect == widget.dialect)
+          .map(
+            (c) => DiscoveredJellyfinServer(
+              address: c.baseUrl,
+              id: c.serverMachineId,
+              name: c.serverName,
+              dialect: c.dialect,
+            ),
+          );
 
       final factory = widget._localDiscoveryFactory;
       final lanServers = factory != null