Add field engagement and accountable reframing

[davidahmann]

Summary

• add a field-engagement playbook for finding the process knower, observing representative work, and reconciling sold, stated, observed, system-enforced, and policy-authorized claims
• add a governed engagement-reframe schema, template, worked case, semantic validator, and fail-closed regression tests
• wire accountable reframing through controls, discovery artifacts, skills, capability guidance, public navigation, release gates, and v1.18.0 release metadata

Validation

• npm ci --ignore-scripts
• npm test
• git diff --check

All local gates pass on commit f857f5e.