feat(brand): swap header icon for real Cameleer logo

Placeholder 3-wavy-lines SVG replaced with the product logo
(camel + cameleer figure + compass rose).

src/components/SiteHeader.astro

@@ -4,14 +4,14 @@ import CTAButtons from './CTAButtons.astro';
 <header class="sticky top-0 z-40 backdrop-blur-md bg-bg/80 border-b border-border">
   <div class="max-w-content mx-auto px-6 h-16 flex items-center justify-between gap-6">
     <a href="/" class="flex items-center gap-2 group" aria-label="Cameleer home">
-      <svg width="28" height="28" viewBox="0 0 32 32" aria-hidden="true">
-        <rect width="32" height="32" rx="6" fill="#0c111a"/>
-        <g fill="none" stroke="#f0b429" stroke-width="1.6" stroke-linecap="round">
-          <path d="M4 10 Q10 6 16 12 T28 10"/>
-          <path d="M4 16 Q10 12 16 18 T28 16"/>
-          <path d="M4 22 Q10 18 16 24 T28 22"/>
-        </g>
-      </svg>
+      <img
+        src="/cameleer-logo.svg"
+        width="32"
+        height="32"
+        alt=""
+        decoding="async"
+        class="shrink-0"
+      />
       <span class="font-sans font-bold text-lg tracking-tight text-text group-hover:text-accent transition-colors">Cameleer</span>
     </a>
     <nav class="flex items-center gap-8 text-sm" aria-label="Primary">