Auris v0.5.8

diag(recorder): log peak amplitude per track (0.5.8) (#30)

mic captures duration-correct samples but transcript is empty — need to know if
those samples are real audio or digital silence (wrong/silent input device or
autoconvert producing zeros). capture_loop now logs peak=|sample| per track:
~0 = silence, large = real signal. Decides whether to fix device/capture vs it
was just a short/silent take.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>