DeployWatcher consumes GalaxyRepositoryClient.WatchDeployEventsAsync,
suppresses the bootstrap event, and raises RediscoveryEventArgs whenever
time_of_last_deploy actually changes. Reconnect-on-error with capped
exponential backoff. GalaxyDriver wiring (IRediscoverable.OnRediscoveryNeeded
event + StartAsync inside InitializeAsync) lands in a follow-up so this PR
doesn't conflict with the parallel runtime track.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
