format: apply repo prettier (3.8.1) to the folded skills tree

963 markdown files reformatted with the repository's pinned prettier so
pnpm format:check covers the folded tree like every other repo file.

The formatter's embedded-language pass also normalized code fences
(TS semicolons, closed HTML tags in examples, lowercased CSS hex colors,
one renumbered list that skipped an index). Alphanumeric token deltas vs
the fold commit were audited file-by-file; all are formatter-equivalent
markup normalizations plus the four sanitized skills.

packages/mosaic/framework/skills/vercel-react-best-practices/rules/rerender-derived-state.md

@@ -13,9 +13,9 @@ Subscribe to derived boolean state instead of continuous values to reduce re-ren
 
 ```tsx
 function Sidebar() {
-  const width = useWindowWidth()  // updates continuously
-  const isMobile = width < 768
-  return <nav className={isMobile ? 'mobile' : 'desktop'} />
+  const width = useWindowWidth(); // updates continuously
+  const isMobile = width < 768;
+  return <nav className={isMobile ? 'mobile' : 'desktop'} />;
 }
 ```
 
@@ -23,7 +23,7 @@ function Sidebar() {
 
 ```tsx
 function Sidebar() {
-  const isMobile = useMediaQuery('(max-width: 767px)')
-  return <nav className={isMobile ? 'mobile' : 'desktop'} />
+  const isMobile = useMediaQuery('(max-width: 767px)');
+  return <nav className={isMobile ? 'mobile' : 'desktop'} />;
 }
 ```