- Config write serialization via _writeQueue prevents concurrent
read-modify-write races between settings/queue/history saves
- Cancel active uploads on app quit (prevents zombie processes)
- Persist queue before update install (prevents queue loss)
- Sync IPC save in beforeunload (guarantees save before close)
- Fix double configStore.load() call
- Guard against status regression in handleProgress (done→uploading)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>