Implement IAsyncDisposable on GalaxyDriver so async sub-component disposals
(EventPump, AlarmFeed, MxSession, MxClient, RepositoryClient) are awaited rather
than blocked on GetAwaiter().GetResult(). DisposeAsync is now the primary path;
Dispose() delegates to it for using-statement compatibility. Each async component's
shutdown is awaited individually with a best-effort catch so a single slow shutdown
cannot prevent the rest of the cleanup sequence from running.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
d572a011ef