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>

mkdocs.yml

@@ -11,20 +11,18 @@ theme:
   name: material
   custom_dir: docs/overrides
   palette:
-    - media: "(prefers-color-scheme)"
-      scheme: slate
-      primary: deep purple
-      accent: deep purple
-      toggle:
-        icon: material/brightness-4
-        name: Switch to light mode
-    - media: "(prefers-color-scheme: light)"
-      scheme: default
-      primary: deep purple
-      accent: deep purple
+    - scheme: default
+      primary: custom
+      accent: custom
       toggle:
         icon: material/brightness-7
         name: Switch to dark mode
+    - scheme: slate
+      primary: custom
+      accent: custom
+      toggle:
+        icon: material/brightness-4
+        name: Switch to light mode
   font:
     text: Inter
     code: JetBrains Mono