WIP: site redesign, odoc extension API updates, and new content

- odoc extension API: add link-phase enrichment support for extensions
- odoc-jons-plugins: new site shell with nav bar, recent posts with
featured card layout, and updated CSS
- site-builder: support projects/ directory and improved rule generation
- site: redesigned homepage with hero section and recent posts cards
- site: updated blog index layout
- onnxrt docs: minor .mld cleanup
- New blog images and content (weeknotes, examination map, fungus svg)
- Add mockup.html for design iteration

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>