feat: stage 2 real CAD conveyor, hybrid physics drops, mobile policy (WIP)

- CAD pipeline: conveer.FCStd -> FreeCAD headless -> conveyor-web.glb
  (555KB Draco, 42 named nodes) integrated into main scene; gates and
  rollers animated from domain state
- Domain-driven adapter sorterVisualState.ts; per-SKU visual physics
  profiles (VISUAL_PHYSICS_ESTIMATE)
- Hybrid Rapier physics: kinematic belt travel -> dynamic drop handoff
  -> verified freeze; shared collider layout (physicsWorldLayout) used
  by runtime and headless validation sim (physicsDropSim + 13 tests)
- Gravity chutes / open roll-cage front redesign (drop tuning in progress:
  4/7 routes verified headless)
- Premium industrial visual: PBR, ACES, PCFSoft shadows, Lightformer env,
  UI cleanup behind ?debug=1
- Mobile capability policy: SVG fallback / Mobile Low / full tiers,
  Telegram WebView forced to SVG, e2e stubs for weak devices
- Performance benchmarks cad-light/physics/full pass; stage2 artifacts

tsc clean. Physics drop validation for 3 SKU routes still in progress.

Co-authored-by: Cursor <cursoragent@cursor.com>

.gitignore

@@ -21,3 +21,5 @@ playwright-report/
 blob-report/
 releases/backup-*/
 scripts/.perf-tmp.cjs
+tools/stage2-cad/out/
+__pycache__