Converts a target repo's provider-specific instruction file (CLAUDE.md,
.cursor/rules, copilot-instructions.md, etc.) into a thin adapter over
AGENTS.md, mirroring this repo's own two-tier CLAUDE.md pattern
(ADR-0002/0003). Self-validates via a bundled deterministic script
(scripts/validate-adapter.sh) rather than a separate paired audit skill.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
