Add Specs section, Reflexive Web essay, fix highlight and dev caching

- Fix highlight() returning SxExpr so syntax-highlighted code renders
  as DOM elements instead of leaking SX source text into the page
- Add Specs section that reads and displays canonical SX spec files
  from shared/sx/ref/ with syntax highlighting
- Add "The Reflexive Web" essay on SX becoming a complete LISP with
  AI as native participant
- Change logo from (<x>) to (<sx>) everywhere
- Unify all backgrounds to bg-stone-100, center code blocks
- Skip component/style cookie cache in dev mode so .sx edits are
  visible immediately on refresh without clearing localStorage

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

sx/sxc/home.sx

@@ -3,14 +3,14 @@
 (defcomp ~sx-hero (&key &rest children)
   (div :class "max-w-4xl mx-auto px-6 py-16 text-center"
     (h1 :class "text-5xl font-bold text-stone-900 mb-4"
-      (span :class "text-violet-600 font-mono" "(<x>)"))
+      (span :class "text-violet-600 font-mono" "(<sx>)"))
     (p :class "text-2xl text-stone-600 mb-8"
       "s-expressions for the web")
     (p :class "text-lg text-stone-500 max-w-2xl mx-auto mb-12"
       "A hypermedia-driven UI engine that combines htmx's server-first philosophy "
       "with React's component model. S-expressions over the wire — no HTML, no JavaScript frameworks.")
-    (div :class "bg-stone-50 border border-stone-200 rounded-lg p-6 text-left font-mono text-sm overflow-x-auto"
-      (pre :class "leading-relaxed" children))))
+    (div :class "bg-stone-100 rounded-lg p-6 text-left font-mono text-sm mx-auto max-w-2xl"
+      (pre :class "leading-relaxed whitespace-pre-wrap" children))))
 
 (defcomp ~sx-philosophy ()
   (div :class "max-w-4xl mx-auto px-6 py-12"