0.3.3

fix(v0.3.3): crash-on-launch on Apple Silicon (quarantine strip)

The in-app update downloader (v0.3.1+) was opening the downloaded
DMG with its com.apple.quarantine extended attribute intact. On
Apple Silicon, an ad-hoc signed app that retains quarantine is
killed on launch by amfid — no window, no error, just a crash.

Fix: run 'xattr -cr' on the downloaded DMG before shell.openPath()
so the mounted app bundle launches clean.

Also adds:
- docs/CRASH_DIAGNOSIS.md (root cause + fixes for handoff)
- CHANGELOG.md (full project history)