Sung chorus toolchain (sing.py WORLD vocoder + render script); ignore venv/journey artifacts

▶ Play it: Perforated Afterlife — the anchor authored from a measured corpus of real melodies https://stellate.app/?genre=ragtime&seed=8933&path=753.14435,772.14468,734.14468&xdur=13.122

410ca5d https://github.com/aboard-io/stellate/commit/410ca5ddb82b65b9847efce9f40b0307f3c51812