Fix subtitle-cycle OSD labels and harden quality gates

- Resolve J/Shift+J subtitle-cycle OSD text via track-list labels and property expansion
- Add mpv proxy OSD runtime + regression coverage across IPC/main/runtime paths
- Scope `make pretty` to maintained source files and add scoped Prettier script
- Align release workflow with cache/install order and explicit TypeScript check
- Clean up duplicate submodule entry and remove checked-in docs/plans artifacts

src/main-entry-runtime.test.ts

@@ -16,10 +16,7 @@ test('normalizeStartupArgv defaults no-arg startup to --start --background', ()
     '--background',
   ]);
   assert.deepEqual(
-    normalizeStartupArgv(
-      ['SubMiner.AppImage', '--password-store', 'gnome-libsecret'],
-      {},
-    ),
+    normalizeStartupArgv(['SubMiner.AppImage', '--password-store', 'gnome-libsecret'], {}),
     ['SubMiner.AppImage', '--password-store', 'gnome-libsecret', '--start', '--background'],
   );
   assert.deepEqual(normalizeStartupArgv(['SubMiner.AppImage', '--background'], {}), [