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-frontend/lib/types.ts

@@ -93,6 +93,16 @@ export interface ProviderCapabilities {
   search: boolean;
   streaming_protocol: StreamingProtocol;
   rescan: boolean;
+  transcode: boolean;
+}
+
+export interface TranscodeSettings {
+  cleanup_ttl_hours: number;
+}
+
+export interface TranscodeStats {
+  cache_size_bytes: number;
+  item_count: number;
 }
 
 export interface ProviderInfo {