Fix CI: title removal order, Windows fixtures and POSIX-only tests

- Title removal ran the Steam shortcut tidy-up before steamos-delete, which
  finds the Proton prefix through that shortcut, so compatdata was left behind
  (e2e caught it). steamos-delete runs first again; art/collection tidy-up after.
- Test fixtures are byte-exact: never convert line endings (a text-looking
  fixture APK got CRLF on Windows and failed its SHA-256).
- Read index.html/artwork-settings.js as UTF-8 in tests; app-data backup and
  OBB shell tests run only on POSIX (they exercise the Frame-side scripts).
- e2e expects the icon under artwork/ now.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/e2e/test_android.py

@@ -33,7 +33,7 @@ class AndroidApps(harness.FrameTestCase):
         self.assertEqual(shortcut['name'], 'App label')
         self.assertEqual(shortcut['exe'], f'{APP_DIR}/launch.sh')
         self.assertEqual(shortcut['start_dir'], APP_DIR)
-        self.assertEqual(shortcut['icon'], f'{APP_DIR}/icon.png')
+        self.assertEqual(shortcut['icon'], f'{APP_DIR}/artwork/icon.png')
         for f in ('app.apk', 'launch.sh', 'instance.id', 'meta.json', 'icon.png', 'lepton-show-flatscreen'):
             self.assertTrue(exists(f'{APP_DIR}/{f}'), f)
         self.assertEqual(meta['game_id'], (meta['shortcut'] << 32) | 0x02000000)