feat(docs): comprehensive GitHub Primer theme overhaul with dark mode fix

- Fix broken dark mode by correcting palette toggle order and setting primary/accent to custom
- Rewrite extra.css with full GitHub Primer color scheme (light: #ffffff/#0969da, dark: #0d1117/#1f6feb)
- Style header, sidebar, buttons, cards, code blocks, and tables to match GitHub aesthetic
- Add Open Graph and Twitter Card meta tags via main.html override
- Add JSON-LD structured data (WebSite + SoftwareApplication schemas)
- Add announcement bar (v2.1.2 release)
- Add custom 404 page with navigation buttons
- Remove inline styles from skills/index.md (moved to extra.css)
- Mobile responsive adjustments for hero sections

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

docs/overrides/404.html

@@ -0,0 +1,19 @@
+{% extends "main.html" %}
+
+{% block content %}
+<div style="text-align: center; padding: 4rem 1rem;">
+  <h1 style="font-size: 6rem; font-weight: 800; margin-bottom: 0.5rem; opacity: 0.15; line-height: 1;">404</h1>
+  <p style="font-size: 1.1rem; margin-bottom: 0.5rem; font-weight: 600;">
+    Page not found
+  </p>
+  <p style="font-size: 0.9rem; opacity: 0.6; margin-bottom: 2rem;">
+    The page you're looking for doesn't exist or has been moved.
+  </p>
+  <a href="{{ config.site_url }}" class="md-button md-button--primary">
+    Back to Home
+  </a>
+  <a href="{{ config.site_url }}skills/" class="md-button">
+    Browse Skills
+  </a>
+</div>
+{% endblock %}

docs/overrides/main.html

@@ -9,4 +9,55 @@
   gtag('js', new Date());
   gtag('config', 'G-VHRY2VKY9K');
 </script>
+
+{% if page and page.meta %}
+<!-- Open Graph -->
+<meta property="og:type" content="website" />
+<meta property="og:title" content="{{ page.meta.title or page.title }} - {{ config.site_name }}" />
+<meta property="og:description" content="{{ page.meta.description or config.site_description }}" />
+<meta property="og:url" content="{{ page.canonical_url }}" />
+<meta property="og:site_name" content="{{ config.site_name }}" />
+
+<!-- Twitter Card -->
+<meta name="twitter:card" content="summary_large_image" />
+<meta name="twitter:title" content="{{ page.meta.title or page.title }} - {{ config.site_name }}" />
+<meta name="twitter:description" content="{{ page.meta.description or config.site_description }}" />
+<meta name="twitter:site" content="@nginitycloud" />
+{% endif %}
+
+<!-- JSON-LD Structured Data -->
+<script type="application/ld+json">
+{
+  "@context": "https://schema.org",
+  "@type": "WebSite",
+  "name": "{{ config.site_name }}",
+  "url": "{{ config.site_url }}",
+  "description": "{{ config.site_description }}",
+  "author": {
+    "@type": "Person",
+    "name": "{{ config.site_author }}"
+  }
+}
+</script>
+<script type="application/ld+json">
+{
+  "@context": "https://schema.org",
+  "@type": "SoftwareApplication",
+  "name": "Claude Code Skills",
+  "applicationCategory": "DeveloperApplication",
+  "operatingSystem": "Cross-platform",
+  "description": "{{ config.site_description }}",
+  "url": "{{ config.site_url }}",
+  "author": {
+    "@type": "Person",
+    "name": "{{ config.site_author }}"
+  },
+  "license": "https://opensource.org/licenses/MIT",
+  "offers": {
+    "@type": "Offer",
+    "price": "0",
+    "priceCurrency": "USD"
+  }
+}
+</script>
 {% endblock %}

docs/overrides/partials/announce.html

@@ -0,0 +1,3 @@
+<a href="https://github.com/alirezarezvani/claude-skills/releases/tag/v2.1.2">
+  <strong>v2.1.2</strong> — 173 skills across 9 domains. Landing page generator now outputs Next.js TSX + Tailwind CSS!
+</a>