docs: add canonical documentation + audit cleanup
- AGENTS.md: canonical project entry point (Quick Nav, pipeline, constraints)
- docs/: complete docs tree — architecture, API spec, DB schema, infra,
runbook, requirements, tech stack, principles, reference ADRs, guides,
tasks backlog, testing strategy
- tests/README.md: test commands, structure, known gaps
- README.md / CLAUDE.md / DEPLOYMENT.md: updated with canonical doc links
- .archive/: backup of pre-documentation-pipeline originals
- backend/uv.lock: uv dependency lockfile
- Delete committed __pycache__ .pyc files (should have been gitignored)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
a3b300b76a