Show the app as Starsync (window titles, launcher entry, About, README); internals unchanged

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

apps/desktop/lib/src/jellyfin/accounts.dart

@@ -8,7 +8,6 @@ import 'package:hive_ce/hive.dart';
 import 'package:sync_relay_core/core.dart';
 
 import '../screens/home/picked_media.dart';
-import '../screens/home/ui.dart' show appName;
 import '../update/updater.dart' show appVersion;
 
 // Linked Jellyfin servers, one account per ServerId, in their own Hive box.
@@ -215,7 +214,8 @@ class JellyfinAccounts extends ChangeNotifier {
   String get deviceId => _deviceId;
 
   JellyfinClientInfo get clientInfo => JellyfinClientInfo(
-        client: appName,
+        // The old name on purpose: Jellyfin lists devices under it.
+        client: 'Watch Together',
         device: deviceName ?? _hostname(),
         deviceId: _deviceId.isEmpty ? 'unknown' : _deviceId,
         version: appVersion,

apps/desktop/lib/src/platform/desktop_entry.dart

@@ -44,7 +44,7 @@ Future<void> installDesktopEntry({String? executable, String? dataHome, String?
 @visibleForTesting
 String desktopEntryText(String exe) => '''[Desktop Entry]
 Type=Application
-Name=Watch together
+Name=Starsync
 Comment=Watch videos in sync with friends
 Exec="$exe"
 Icon=$appId

apps/desktop/lib/src/screens/home/ui.dart

@@ -1,7 +1,7 @@
 import 'package:flutter/material.dart';
 
 /// Product name (working title). Change it here only.
-const appName = 'Watch Together';
+const appName = 'Starsync';
 
 const repoUrl = 'https://git.senkochan.moe/Foxyz/sync_replay_project';