docs: make question contracts executable

[douglasmonsky]

Summary

• add the validated 40-question agent-kernel registry and Draft 2020-12 schema
• generate a deterministic 14,459-byte model guidance projection
• enforce Markdown reconciliation, evidence selectors, support/stage rules, dependency completeness, and raw/SQL exclusions
• wire the checker into repository scope/static/test gates and close CK-01 accounting

Validation

• 36 focused contract/scope/documentation tests passed
• just v: 473 tests plus scope, static, frontend, maintainability, and release-safety gates passed
• Ruff, MyPy, and Pyright passed
• exact build/release checks passed
• wheel: 174,985 bytes, SHA-256 392157d90eb5d1071ced228ae2ddf6f8237e73e3ec2870937b3bca12c77a2539
• sdist: 476,169 bytes, SHA-256 ed362a6911ad0df68680934ddb3640612c0c8f9966c149c4ce5db27af29b88ad

Review

One final review produced 5 findings; all 5 were accepted and resolved. Reviewer-token attribution is pending because the installed Usage Tracker CLI lacks the metrics helper's expected strict command.