Add not-prose to all code blocks to enforce stone-100 background

Tailwind's prose class applies dark backgrounds to pre/code elements,
overriding the intended bg-stone-100. Adding not-prose to every code
container div across docs, specs, and examples pages.

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

sx/sxc/examples.sx

@@ -12,7 +12,7 @@
   (div :class "border border-dashed border-stone-300 rounded p-4 bg-stone-100" children))
 
 (defcomp ~example-source (&key code)
-  (div :class "bg-stone-100 rounded p-5 mt-3 mx-auto max-w-3xl"
+  (div :class "not-prose bg-stone-100 rounded p-5 mt-3 mx-auto max-w-3xl"
     (pre :class "text-sm leading-relaxed whitespace-pre-wrap break-words" (code code))))
 
 ;; --- Click to load demo ---