Design cleanup + lighter MP3 export (lamejs instead of ffmpeg.wasm)

Design: rebuilt the stylesheet around a calmer, cohesive system — one restrained vaporwave palette, consistent spacing/type scale, color reserved for the tiles (not glowing everywhere), tidy section blocks, a labeled sources table (column headers), cleaner popover/editor, verifier, and transport.

MP3 — replaced ffmpeg.wasm (~30MB core + worker + COOP/COEP) with lamejs, a pure-JS LAME encoder (~50KB). wavToMp3 parses the rendered WAV (16-bit, mono/stereo) and LAME-encodes it.

▶ Play it: Food Court Eternity — parked on the genre this change names https://stellate.app/?genre=vaporwave&seed=2534&path=1679.4393,1698.4426,1660.4426&xdur=13.122

f981d93 https://github.com/aboard-io/stellate/commit/f981d9366abde045411dc220e1c0a209331be84c