feat: add dark theme support and update homepage content

- Integrated next-themes for dark mode theming with default dark theme
- Added new UI components (GridBlink, Spotlight) and enhanced world map with cyan glow effects
- Updated homepage messaging to emphasize Mycelium as a living network with new audience imagery

tailwind.config.js

@@ -1,5 +1,6 @@
 /** @type {import('tailwindcss').Config} */
 export default {
+  darkMode: 'class',
   content: [
     "./index.html",
     "./src/**/*.{js,ts,jsx,tsx}",