Increase home page skills area height and set a 4-column grid at desktop sizes.
This gives the catalog section more visible space on scroll and improves row utilization
on larger screens without altering filtering/search behavior.
* feat: add support for GFM and highlight in markdown rendering
* feat: enhance markdown rendering by splitting YAML frontmatter and body
* feat: improve markdown styling for light and dark themes
* feat: enhance frontmatter parsing and display in SkillDetail component
Consolidate the repository into clearer apps, tools, and layered docs areas so contributors can navigate and maintain it more reliably. Align validation, metadata sync, and CI around the same canonical workflow to reduce drift across local checks and GitHub Actions.
