[laneC] M4: audio mux, graft_limb.py, MODELBEAST proxy
- render/end muxes scene audio[] (adelay+volume+amix, aac, -shortest);
audio paths path-guarded; render.js finalRender passes scene audio
- scripts/graft_limb.py: headless Blender limb graft (align root->target bone,
join armatures, parent-keep-offset, join meshes; refusal exit 2 on mitten
overlap; drops phantom importer icosphere; no finish/decimate). --selftest
builds synthetic fixtures + verifies both paths under Blender
- /mb/submit MODELBEAST proxy (SCENEGOD_MB=1 gated, token from ~/Documents/
backnforth/.env at request time never logged, /api/assets->/api/jobs)
- test_server.py: +audio-stream, +MB gating & two-step contract (mock MB);
8 groups green
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
be65355f6b