20260903T1738Z docs local site

What. The docs render as a local static site: make docs serves them with live reload, make docs-build builds in strict mode and fails on a broken internal link. MkDocs Material plus awesome-nav in a docs dependency group. The README (as home page) and changelog/ enter the site through symlinks under docs/; a small hook rewrites their repo-relative links for the site layout. Nav order follows the read order in CLAUDE.md. Nothing is hosted and no CI runs this (decided with Nacho, 2026-09-03: local only for now).

Why. The docs are the product until code exists, and a rendered site with search and navigation is easier to review than raw Markdown. Strict builds turn broken cross-references into an error instead of a silent drift.

Verify. make docs-build exits 0 with no warnings; make docs and open http://127.0.0.1:8000.