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

.gitmodules

@@ -5,9 +5,6 @@
 [submodule "vendor/yomitan-jlpt-vocab"]
 	path = vendor/yomitan-jlpt-vocab
 	url = https://github.com/stephenmk/yomitan-jlpt-vocab
-[submodule "yomitan-jlpt-vocab"]
-	path = vendor/yomitan-jlpt-vocab
-	url = https://github.com/stephenmk/yomitan-jlpt-vocab
 [submodule "vendor/subminer-yomitan"]
 	path = vendor/subminer-yomitan
 	url = https://github.com/ksyasuda/subminer-yomitan