Hartmut
5d912594dd
docs: add milestones, file targets, acceptance gates to all 10 ROADMAP priorities
- Each priority now has: milestones (M1-MN), concrete file target table
(CREATE/MODIFY/DELETE per file), and binary acceptance gates
- Created docs/plans/0001-step-to-usd-implementation.md: full execution
checklist for USD pipeline (Priorities 2, 4, 5) with:
- Phase 1: dual-write USD beside GLB
- Phase 2: partKey + three-layer material assignment model
- Phase 3: seam/sharp payload to USD mesh primvars (index-space)
- Phase 4: Blender render from USD
- Phase 5: frontend ThreeDViewer partKey migration
- Open questions decision table
- Non-regression checklist
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>