Desktop: video freeze recovery, session fixes, Home redesign

- Player + VideoController per session; Reload video (Ctrl+R) and a
  frozen-picture watchdog that reloads automatically.
- Shortcuts no longer fire while typing; empty swap disabled;
  hwdec setting/env actually applied.
- Idle unready measured from real inactivity; cancellable reconnects
  and setup; ready restored from server state; kicked/failed host
  stops its server; graceful leave on window close; no URLs with
  keys in display names.
- Welcome + connect screens replaced by one Home screen with Join and
  Host cards, recent servers, Settings, Integrations and About.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/desktop/lib/app.dart

@@ -1,9 +1,9 @@
 import 'package:flutter/material.dart';
 import 'package:signals/signals_flutter.dart';
 
-import 'src/screens/connect_screen.dart';
+import 'src/screens/home/home_screen.dart';
+import 'src/screens/home/ui.dart';
 import 'src/screens/session_screen.dart';
-import 'src/screens/welcome_screen.dart';
 import 'src/state/session_state.dart';
 
 class WatchTogetherApp extends StatelessWidget {
@@ -13,13 +13,12 @@ class WatchTogetherApp extends StatelessWidget {
   Widget build(BuildContext context) {
     final session = SessionState.instance;
     return MaterialApp(
-      title: 'Watch Together',
+      title: appName,
       theme: ThemeData.dark(),
       home: SignalBuilder(
         builder: (context) {
           return switch (session.route.value) {
-            AppRoute.welcome => const WelcomeScreen(),
-            AppRoute.connect => const ConnectScreen(),
+            AppRoute.home => const HomeScreen(),
             AppRoute.session => const SessionScreen(),
           };
         },