feat: make docs theme-aware using CSS variables

- Update Tailwind config to use CSS variables instead of hardcoded colors
- Colors now reference theme variables: var(--text-primary), var(--text-secondary), etc.
- Fix Tokyo Night theme: text-secondary corrected from #565f89 to #9aa5ce
- Typography plugin now uses var() for theme-aware prose styling
- Enables docs to respect theme system like rest of app

web/static/input.css

@@ -17,7 +17,7 @@
     --bg-primary: #1a1b26;
     --bg-secondary: #16161e;
     --text-primary: #a9b1d6;
-    --text-secondary: #565f89;
+    --text-secondary: #9aa5ce;
     --accent: #7aa2f7;
     --border: #414868;
   }