web: show the WebRTC toggle and transport in the web UI

The web client now speaks WebRTC, but the desktop settings page hides
the punch options on web and the remote page opens without the session
tab that carries the transport name. Let the existing "Enable WebRTC P2P
connection" checkbox through on web (the other punch options stay
native-only), and add a Transport row to the quality monitor for WebRTC
sessions only (with "(TURN)" when ICE relayed), on every platform.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JXJJGEGdgu26wgCppvUXdZ

flutter/lib/desktop/pages/desktop_setting_page.dart

@@ -581,12 +581,15 @@ class _GeneralState extends State<_General> {
           kOptionEnableIpv6Punch,
           isServer: false,
         ),
+      ],
+      if (!incomingOnly)
         _OptionCheckBox(
           context,
           'Enable WebRTC P2P connection',
           kOptionEnableWebrtc,
           isServer: false,
         ),
+      if (!isWeb && !incomingOnly)
         Tooltip(
           message: translate('sync-clipboard-between-sessions-tip'),
           child: _OptionCheckBox(
@@ -596,7 +599,6 @@ class _GeneralState extends State<_General> {
             isServer: false,
           ),
         ),
-      ],
     ];
 
     // Add client-side wakelock option for desktop platforms