* feat: restructure schemas as directories with templates
Move built-in schemas from embedded TypeScript objects to a file-based
directory structure. This enables co-located templates alongside schemas.
Changes:
- Remove builtin-schemas.ts (replaced by file-based schemas)
- Add schemas/ directory at package root with spec-driven and tdd schemas
- Update resolveSchema() to load from directory structure
- Resolution checks user dir → package dir
* chore: archive restructure-schema-directories change
* docs: update artifact_poc.md for directory-based schema structure
Update documentation to reflect the new schema structure where schemas
are directories containing schema.yaml and co-located templates/ rather
than single .yaml files with separate template directories.
Add internal documentation for the artifact-based approach to OpenSpec
core. This document outlines design decisions, terminology, and the
philosophy behind treating dependencies as enablers rather than gates.