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/test/text_focus_test.dart

@@ -0,0 +1,33 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:watch_together/src/widgets/text_focus.dart';
+
+void main() {
+  // Regression: the old FocusNode-parent walk never met EditableText, so
+  // session shortcuts (Space, arrows, F) fired while typing in chat.
+  testWidgets('text field focus is detected, buttons are not', (tester) async {
+    final field = FocusNode();
+    final button = FocusNode();
+    await tester.pumpWidget(MaterialApp(
+      home: Scaffold(
+        body: Column(children: [
+          TextField(focusNode: field),
+          TextButton(focusNode: button, onPressed: () {}, child: const Text('b')),
+        ]),
+      ),
+    ));
+    expect(textInputFocused(), isFalse);
+
+    field.requestFocus();
+    await tester.pump();
+    expect(field.hasPrimaryFocus, isTrue);
+    expect(textInputFocused(), isTrue);
+
+    button.requestFocus();
+    await tester.pump();
+    expect(textInputFocused(), isFalse);
+
+    field.dispose();
+    button.dispose();
+  });
+}