Two-tier module prewarm: kill the genre-entry hitch cheaply

The 2026-07-04 regression hunt (Paul: "rendering crackles have returned" + "the scheduler seems slightly off") found NO engine regression

• Fix, measured into shape: full-node-prewarming the heavy voices tanked the load gate (0.987 -> 0.82-0.87

• Vinyl crackle on high-crackle genres (lofi .52, blues .36) renders at exactly the fixed level by design — if it reads too hot by ear, the knob is fx_bus.dsp:55, a deliberate re-voicing not a repair.

▶ Play it: Dust Census — parked on the genre this change names https://stellate.app/?genre=lofi&seed=1821&path=263.9049,282.9082,244.9082&xdur=13.122

82bb1d5 https://github.com/aboard-io/stellate/commit/82bb1d55f840b7f4f363b1e96edbe5a29e8077e6