feat: add local files provider with indexing and rescan functionality

- Implemented LocalFilesProvider to manage local video files.
- Added LocalIndex for in-memory and SQLite-backed indexing of video files.
- Introduced scanning functionality to detect video files and extract metadata.
- Added API endpoints for listing collections, genres, and series based on provider capabilities.
- Enhanced existing routes to check for provider capabilities before processing requests.
- Updated frontend to utilize provider capabilities for conditional rendering of UI elements.
- Implemented rescan functionality to refresh the local files index.
- Added database migration for local files index schema.

k-tv-backend/api/src/dto.rs

@@ -46,6 +46,7 @@ pub struct TokenResponse {
 #[derive(Debug, Serialize)]
 pub struct ConfigResponse {
     pub allow_registration: bool,
+    pub provider_capabilities: domain::ProviderCapabilities,
 }
 
 // ============================================================================