Three issues fixed:
1. asBytes() helper for []interface{} → []byte conversion — same
float64 deserialization issue as numeric fields. Cover art data
from the frontend arrives as []interface{} of float64, not []byte.
2. DB sync for cover art — was a placeholder no-op. Now saves image
to covers cache dir (content-hash dedup + thumbnail generation),
upserts cover_art row, and updates release_groups.cover_art_id.
Clear sets cover_art_id to NULL on linked release groups.
3. Frontend ReadFile returns base64 string (Go []byte JSON encoding),
not number[]. Decode with atob() before creating Uint8Array for
preview blob URL.
After saveEdit() succeeds, re-fetch tracks from library store and update
this.track with the fresh data so the dialog shows updated values instead
of the stale snapshot passed via show().
- Wire saveEdit() to WriteTrackTagsByPath with diff-only TagChanges map
- Add cover art selection via ImageFilePicker with instant blob preview
- Add cover art removal (× button) with clearCoverArt state
- Show saving indicator and disable buttons during save
- Display errors inline in action bar; edit mode stays active on error
- Add ReadFile Go method on FrontendUtil to read cover art bytes
- Add Wails binding for ReadFile
- Clean up all edit state (editValues, pendingCoverArt, errorMessage) on close/cancel
- cover-grid dynamic text tiers use --yj-text-xs/sm/md/lg tokens
- track-list sort toolbar, row text, and fav icon use design tokens
- queue-panel header and track text use type scale tokens
- track-details, track-info, artist-details, genre-details use tokens
- designTokens imported and prepended to static styles in all 8 files