md2png 0.2.0

Added

• Add silent update discovery in About using public GitHub latest-release
  metadata, a 24-hour successful-result cache, a 60-second manual cooldown, and
  persisted server rate-limit handling. A newer version downloads only after
  explicit confirmation; the app verifies the versioned Apple silicon DMG's
  size and SHA-256 digest before asking macOS to open it for manual installation.
  Verified downloads can be reopened or revealed in Finder for cleanup.

Changed

• Replace the About window's manual Releases link with compact up-to-date or
  available-version status and inline actions. Automatic checking is silent;
  download progress stays in About and the status item, and Releases is a
  failure fallback.
• Give explicit update checks inline progress and recent-completion feedback
  without adding a dialog or changing the displayed release result.