docs: regenerate llms-full.txt with all current docs content (category 7)

The llms-full.txt was stale — created before many recent docs
improvements. Regenerated from all current docs pages in nav order,
with MkDocs-specific markup stripped for clean LLM consumption.
Also added missing pages (changelog, contributing, codebase map)
to llms.txt index.

Co-authored-by: Ralphify <noreply@ralphify.co>

Author: 2 people