[duplicated subtitle][Bug] Fix duplicated subtitle issue

- Add core deduplicated logic/method
- Reproduce bug with the YouTube video: https://www.youtube.com/watch?v=b7vmW_5HSpE
- Introduce `SubtitleDeduplicator.java` to check and remove duplicates, storing results in cache.
- Add `SubtitleOrigin` and `SubtitleState` enums to model subtitle type and state.
- Ensure cache directory is recreated if missing.

Author: TransZAllen