Deploy the MP3 diet to stellate.app; manifests leave the immutable set

First real exercise of the MEDIA_MANIFEST invariant caught a script bug: the manifest hashed found/*.json alongside the media, but manifests are MUTABLE by design (nginx serves them no-cache — they map names; only the named bytes are immutable). .json now excluded from the invariant set.

• Production-verified: headless chromium rode vaporwave on live stellate.app — crossOriginIsolated, MP3 beds fetched 200 + decoded, maxRms 0.207, zero errors.

▶ Play it: Food Court Eternity — parked on the genre this change names https://stellate.app/?genre=vaporwave&seed=3566&path=1679.4393,1698.4426,1660.4426&xdur=13.122

bffe430 https://github.com/aboard-io/stellate/commit/bffe430e2121bb1fd5e8b891cf3d0a3fd89166d3