docs(structure): add requirements contract, job namespaces, and enforcement gate
Phase 1 scaffold for the docs consolidation:
- docs/STRUCTURE.md: artifact registry, 8 owner-job ID namespaces, routing and change rules
- docs/REQUIREMENTS.md, docs/MILESTONES.md: normative schema, empty pending Phase 2 port
- docs/_templates/: requirement-row, capability, contract, adr
- docs/capabilities/, docs/contracts/: registered homes
- tools/check_requirements.py: enforces registry, IDs, and traceability
- AGENTS.md: coding paused banner + structure-contract routing rule
- README.md: pointers to the structure/requirements/milestones set
Additive only: no doc moves, no requirement text, no CI wiring yet.
Ty
b42e3cb8ce