The legacy event_cb("connected") call between handshake and audio
preflight was a no-op on the frontend (it enters voice only after the
command resolves) but added noise to failing traces. Replaced with a
connect:connected_event_skipped debug event and added an explicit
connect:android_audio_preflight_start marker so the debug log shows a
clear boundary between handshake completion and audio startup.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>