feat: add [data-demo] attribute, purge all inline CSS from docs

New data-demo attribute for demo blocks in documentation.
Replaced 16 files worth of inline style="" wrappers with <div data-demo>.
Only remaining style= is charts --size data injection (legitimate).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

site/content/docs/reference/utilities.md

@@ -14,7 +14,7 @@ ASW provides a small set of utility attributes for inline adjustments. Rather th
 
 ## Inline Demo
 
-<div style="border:1px solid var(--border,#ccc);padding:1.5rem;border-radius:4px;display:flex;flex-direction:column;gap:0.5rem">
+<div data-demo>
   <p><span data-text="mono">data-text="mono"</span> — monospace font</p>
   <p><span data-text="dim">data-text="dim"</span> — reduced opacity / muted</p>
   <p><span data-text="accent">data-text="accent"</span> — accent colour</p>

site/content/docs/reference/vocabulary.md

@@ -14,7 +14,7 @@ Every `data-*` attribute that ASW recognises is listed here. This is the authori
 
 ## Inline Demo
 
-<div style="border:1px solid var(--border,#ccc);padding:1.5rem;border-radius:4px;overflow-x:auto">
+<div data-demo>
   <table>
     <thead>
       <tr><th>Attribute</th><th>Values</th><th>Effect</th></tr>