Tidy: drop scratch genre-kernel state files, ignore future ones

Remove six unreferenced root *.state.json files left over from `genre-kernel.js track ` runs (the intentional demo sets live in playlist/ and mix/). Add `/*.state.json` so future scratch runs don't get re-committed; the leading slash keeps playlist/ and mix/ states tracked.

• Also removed ~88MB of loose regenerable renders from the working tree (already gitignored, not committed).

▶ Play it: Food Court Eternity — the brightest, most processed corner of the space https://stellate.app/?genre=vaporwave&seed=8138&path=1679.4393,1698.4426,1660.4426&xdur=13.122

a50cd71 https://github.com/aboard-io/stellate/commit/a50cd71a695a9e28cd222993bc7aa6feb800f1fe