Add singleFilenameFormat setting so singles/EPs can use a different filename template than albums. The format editor is reused with custom title/description. Dart selects the correct format based on track.isSingle before passing to Go, so no backend changes needed. Also fix isSingle getter to include all EPs regardless of totalTracks. Closes#271
- Add albumType field to Track model with isSingle getter
- Add separateSingles setting in AppSettings
- Modify _buildOutputDir() to organize into Albums/ and Singles/ folders
- Add UI toggle in download settings page
- Parse album_type/record_type from Spotify and Deezer APIs
When enabled, singles are saved to a separate 'Singles' folder
- Add extension manager, manifest, runtime, providers, settings
- Add extension provider and UI pages (extensions, detail, priority)
- Add download service picker widget
- Add metadata provider priority page
- Add source field to Track model for extension tracking
- Add skipBuiltInFallback manifest option to skip built-in providers
- Update download queue to use source extension first
- Add extension upgrade support without data loss
zarzet