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/Dockerfile

@@ -10,8 +10,8 @@ FROM debian:bookworm-slim
 
 WORKDIR /app
 
-# Install OpenSSL (required for many Rust networking crates) and CA certificates
-RUN apt-get update && apt-get install -y libssl3 ca-certificates && rm -rf /var/lib/apt/lists/*
+# Install OpenSSL, CA certs, and ffmpeg (provides ffprobe for local-files duration scanning)
+RUN apt-get update && apt-get install -y libssl3 ca-certificates ffmpeg && rm -rf /var/lib/apt/lists/*
 
 COPY --from=builder /app/target/release/api .