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/components/Header.tsx

@@ -26,9 +26,9 @@ export function Header() {
   };
 
   return (
-    <header>
+    <header className="bg-transparent">
       <nav>
-                <Container className="relative z-50 flex bg-transparent justify-between py-4">
+                <Container className="flex bg-transparent justify-between py-4">
           <div className="relative z-10 flex items-center gap-16">
             <Link to="/" aria-label="Home">
               <img src={pmyceliumLogo} alt="Mycelium" className="h-8 w-auto" />