sni: expose IconAccessibleDesc and AttentionAccessibleDesc
Modern SNI hosts such as the GNOME AppIndicator extension query IconAccessibleDesc and AttentionAccessibleDesc as optional properties. When they are absent, the host ends up logging missing-property warnings even though the rest of the indicator works.
Expose both properties on the StatusNotifierItem and update them from tray state so they track the current semantic status: recording, paused, idle, syncing, error, or stopped.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>