feat(db,repo,renderer): schema v23 + claude_md_template + ClaudeMd renderer
- Bump SCHEMA_VERSION 22 → 23; add claude_md_template singleton table to
_SYSTEM_SCHEMA and _V22_TO_V23_MIGRATIONS; wire migration + fresh-install seed
- src/repositories/claude_md_template.py: ClaudeMdTemplateRepository (get/set/reset)
mirroring WelcomeTemplateRepository; defensive re-seed in get()
- src/claude_md.py: compute_default_claude_md / render_claude_md /
build_claude_md_context — rich renderer with RBAC-filtered tables, metrics,
and marketplaces; reads override from claude_md_template or falls back to
config/claude_md_template.txt; raises TemplateError on broken override
- config/claude_md_template.txt: default Jinja2 markdown template restored from
PR #167 history (tables, metrics, marketplaces, BQ guidance, corporate memory,
directory structure, per-user footer)
f01eb4143d