Add base/sounds/startup.mp3 (16 kHz mono, 24 kbps, ~11 KB) and play it as the
connect-to-HA chime instead of the wake-word sound. The file is referenced via
a new boot_sound_file substitution so it can be overridden with any URL or local
MP3/FLAC/WAV in the thin config. The media player already decodes MP3
(error_cloud_expired.mp3 ships too), so no decoder change is needed.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
