connection page: the Connect menu offers TCP tunneling, as the peer card does (#16075)

The dropdown beside Connect listed file transfer, camera and terminal
but not port forwarding, so reaching it meant having a card for the
peer. `connect` already takes `isTcpTunneling`; only the menu entry and
the parameter that carries it were missing.

Shown on desktop only. The peer card gates the same entry on `isDesktop`
because `connect` routes a tunnel through the desktop path alone; on web
it would have opened a plain remote session instead.


Claude-Session: https://claude.ai/code/session_01EZ49AbZJYfm8NTp5yDPMab

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

flutter/lib/desktop/pages/connection_page.dart

@@ -330,12 +330,14 @@ class _ConnectionPageState extends State<ConnectionPage>
   void onConnect(
       {bool isFileTransfer = false,
       bool isViewCamera = false,
-      bool isTerminal = false}) {
+      bool isTerminal = false,
+      bool isTcpTunneling = false}) {
     var id = _idController.id;
     connect(context, id,
         isFileTransfer: isFileTransfer,
         isViewCamera: isViewCamera,
-        isTerminal: isTerminal);
+        isTerminal: isTerminal,
+        isTcpTunneling: isTcpTunneling);
   }
 
   /// UI for the remote ID TextField.
@@ -568,6 +570,14 @@ class _ConnectionPageState extends State<ConnectionPage>
                                       '${translate('Terminal')} (beta)',
                                       () => onConnect(isTerminal: true)
                                     ),
+                                    // `connect` routes this through the
+                                    // desktop path only; the peer card gates
+                                    // it the same way.
+                                    if (isDesktop)
+                                      (
+                                        'TCP tunneling',
+                                        () => onConnect(isTcpTunneling: true)
+                                      ),
                                   ]
                                       .map((e) => MenuEntryButton<String>(
                                             childBuilder: (TextStyle? style) =>