Create a new scenario from scratch — guides Phases 1-3 (concept, SCHEMA_DESIGN.md, SCENARIO.md), scaffolds the folder structure, stubs test-data/data-manifest.json, and updates README.md.
Create a new scenario from scratch — guides Phases 1-3 (concept, SCHEMA_DESIGN.md, SCENARIO.md), scaffolds the folder structure, stubs test-data/data-manifest.json, and updates README.md.