Obligation-First v0.6.6

Patch Undici and strengthen release, documentation and evidence checks; preserve Colorado teaching history with an evolution companion.

• manifest.json - machine-readable release package manifest
• sha256.txt - SHA-256 checksum index
• RELEASE_NOTES-v0.6.6.md - release notes and verification summary
• /v1/context.jsonld - JSON-LD context
• /v1/schema/ - JSON Schemas
• /.well-known/assistant-guide.txt - GuideCheck assistant guide

Full changelog