feat(transcoding): add FFmpeg HLS transcoding support

- Introduced `TranscodeManager` for managing on-demand transcoding of local video files.
- Added configuration options for transcoding in `Config` and `LocalFilesConfig`.
- Implemented new API routes for managing transcoding settings, stats, and cache.
- Updated `LocalFilesProvider` to support transcoding capabilities.
- Created frontend components for managing transcode settings and displaying stats.
- Added database migration for transcode settings.
- Enhanced existing routes and DTOs to accommodate new transcoding features.

k-tv-backend/infra/src/lib.rs

@@ -40,4 +40,4 @@ pub use schedule_repository::SqliteScheduleRepository;
 pub use jellyfin::{JellyfinConfig, JellyfinMediaProvider};
 
 #[cfg(feature = "local-files")]
-pub use local_files::{LocalFilesConfig, LocalFilesProvider, LocalIndex, decode_stream_id};
+pub use local_files::{LocalFilesConfig, LocalFilesProvider, LocalIndex, TranscodeManager, decode_stream_id};