- 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
yonlu
265a9ea8ce