refactor: extract hero content from aurora background component

- Separated HomeAurora into pure background component and new HomeHero for content
- Converted aurora to absolute positioned background layer in Layout for homepage
- Removed z-index conflicts and cleaned up background color declarations

src/index.css

@@ -6,9 +6,7 @@
   line-height: 1.5;
   font-weight: 400;
 
-  color-scheme: light dark;
   color: rgba(255, 255, 255, 0.87);
-  background-color: #242424;
 
   font-synthesis: none;
   text-rendering: optimizeLegibility;
@@ -60,7 +58,6 @@ button:focus-visible {
 @media (prefers-color-scheme: light) {
   :root {
     color: #213547;
-    background-color: #ffffff;
   }
   a:hover {
     color: #747bff;