Replace static llms.txt and llms-full.txt with auto-generated versions
that stay in sync with docs on every build. The plugin also generates
per-page .md files for individual page fetching by LLMs.
Both llms.txt and llms-full.txt incorrectly said MIT. Also added lite
variant mention to the description and a warning callout on the AI
engine docs page noting AI tools are unavailable in the lite image.
Update all references across docs, workflows, UI components, and config
to point to the new GitHub org (stirling-image/stirling-image) and Docker
Hub account (stirlingimage/stirling-image) ahead of repo transfer.