Theme post code blocks + a11y fixes (impeccable audit) (#25)

Code blocks in posts rendered with the markdown plugin's default light highlight.js theme — white blocks on the dark ledger. This adds dark velvet pre/code styling and a Westgate-toned syntax palette (gold keywords, ledger-ink titles, muted green strings) for post content and the composer preview.

Also picks up the quick wins from an impeccable audit:

- Visible focus ring on the mobile drawer search (input had `outline: 0` with no replacement)
- Input placeholder contrast raised to pass WCAG 4.5:1; tagsinput placeholder reuses the token instead of `$gray-500`
- `prefers-reduced-motion` block zeroing transitions/animations (there were none before)
- Fixed a stray `</li>` closing a `<div>` in `quick-search-results.tpl`

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: #25
Co-authored-by: vickydotbat <vickydotbat@tutamail.com>
Co-committed-by: vickydotbat <vickydotbat@tutamail.com>

scss/westgate/_pages.scss

@@ -136,7 +136,7 @@ a.sow-card:hover {
 	letter-spacing: 0.08em;
 	text-transform: uppercase;
 	color: var(--wg-gold);
-	background: rgba(194, 163, 90, 0.08);
+	background: var(--wg-border-soft);
 	border: 1px solid var(--wg-gold-soft);
 	border-radius: 4px;
 	padding: 3px 9px;
@@ -654,7 +654,7 @@ a.sow-card:hover {
 	margin-top: var(--wg-space-md);
 	padding: 3px 9px;
 	color: var(--wg-gold);
-	background: rgba(194, 163, 90, 0.08);
+	background: var(--wg-border-soft);
 	border: 1px solid var(--wg-gold-soft);
 	border-radius: 4px;
 }