Rewrites the pages that survive the restructure so they lead with what a reader
can accomplish, and points them at the sections added in the previous commit.
Page set and navigation are unchanged here; only content moves.
Keeps the skill count in README. CLAUDE.md's catalog-maintenance rule requires
the count to live in README and CLAUDE.md, and both now agree with the 19
directories under skills/.
Add a "Video Components" overview to the docs site — an entry point to the
50+ catalog blocks and components: what they are, how to install and wire
them, and how to contribute a new one. Wire it into the Guides sidebar.