Restore the full vaporwave capability: found sound + MP3, as recipe

The earlier pipeline didn't just play synth chords — it layered field recordings from the Internet Archive (radio aporee: Tokyo Station, Tsukiji, Asakusa, a Paris market), granular-processed through syncgrain (stretched, pitched down, into the reverb), arranged as solo interludes where the band…

• royal-road.csd — adds instr 3: syncgrain found-sound layer (Tokyo Station), plus an arrangement with intro/interlude/outro city solos and a haze bed under two Royal Road passes.

• fetch-found-sound.sh — downloads + trims the aporee recordings from the Internet Archive (the recipe; the .ogg/.wav are external, not committed).

• render.sh — now also encodes vaporwave.mp3 (libmp3lame 160k).

• SOURCES.md — archive.org items + CC BY-NC-SA attribution.

▶ Play it: Food Court Eternity — parked on the genre this change names https://stellate.app/?genre=vaporwave&seed=9228&path=1679.4393,1698.4426,1660.4426&xdur=13.122

d7744c9 https://github.com/aboard-io/stellate/commit/d7744c9c33d059e88a00d0f4849995b90b86c04f