28d5a3a9ad
New --echo-test <secs> flag sends a 440Hz tone through relay echo, records the return, and analyzes quality in 5-second windows: - Per-window: frames sent/received, loss %, SNR (dB), correlation - Detects quality degradation over time (compares first vs second half) - Reports jitter buffer stats (depth, lost, late packets) - Diagnoses jitter buffer drift and packet loss accumulation Also exposes jitter_stats() on CallDecoder for diagnostics. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>