New quality.py: analyze the recorded WAV (duration + RMS, stdlib only) and drop
clips that are too short or too quiet before transcribing; after transcribing,
reject the stock phrases Whisper invents on silence ("Thank you.", "Untertitel
…", "Vielen Dank." etc.) on short clips. New [quality] config section
(min_speech_seconds, silence_rms, reject_hallucinations, strip_trailing_punctuation).
Tested: silence rms 38 rejected, speech rms 4656 passes.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
