Restructure step R: the app is Starsync (dev.foxyz.starsync)

- Linux app id dev.foxyz.starsync, binary starsync; Windows starsync.exe,
  company foxyz; server starsync-server; Dart package starsync; archives
  starsync-<ver>-*.
- 1.2.x compatibility: watch_together and watch-together-server
  launchers (Linux) / copies (Windows) in the archive; the updater
  accepts both names and relaunches the new binary; update.sh/.bat use
  whichever server exists.
- First start copies (never moves) the old support folder and this
  app's Hive boxes out of ~/Documents into <support>/hive; a marker
  makes it run once; AppDirs is a port; settings schema version with
  ordered migrations.
- Launcher entry dev.foxyz.starsync.desktop; the old one removed.
- Repository name and URLs unchanged.

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

apps/desktop/test/files_page_test.dart

@@ -7,11 +7,11 @@ import 'dart:typed_data';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:hive_ce/hive.dart';
-import 'package:watch_together/src/files/folder_store.dart';
-import 'package:watch_together/src/files/scanner.dart';
-import 'package:watch_together/src/files/thumbnails.dart';
-import 'package:watch_together/src/files/ui/file_tiles.dart';
-import 'package:watch_together/src/files/ui/files_page.dart';
+import 'package:starsync/src/files/folder_store.dart';
+import 'package:starsync/src/files/scanner.dart';
+import 'package:starsync/src/files/thumbnails.dart';
+import 'package:starsync/src/files/ui/file_tiles.dart';
+import 'package:starsync/src/files/ui/files_page.dart';
 
 // The Files page over a real (tiny) folder tree: the scan runs in-line
 // instead of in an isolate and thumbnails come from a fake loader, so