feat: replace icons with brand assets from design-system v0.1.32

- Replace favicon SVG with official camel-logo.svg from design-system
- Add PNG favicons (32px, 192px) with proper link tags in index.html
- Replace sidebar logo with 48px brand icon (cameleer-logo-48.png)
- Replace sign-in page logo with 48px brand icon
- Permit favicon PNGs in SecurityConfig

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/components/Layout.tsx

@@ -9,26 +9,15 @@ import { useAuth } from '../auth/useAuth';
 import { useScopes } from '../auth/useScopes';
 import { EnvironmentTree } from './EnvironmentTree';
 
-// Simple SVG logo mark for the sidebar header
 function CameleerLogo() {
   return (
-    <svg
+    <img
+      src="/platform/cameleer-logo-48.png"
+      alt=""
       width="24"
       height="24"
-      viewBox="0 0 24 24"
-      fill="none"
-      xmlns="http://www.w3.org/2000/svg"
       aria-hidden="true"
-    >
-      <circle cx="12" cy="12" r="10" fill="currentColor" opacity="0.15" />
-      <path
-        d="M7 14c0-2.5 2-4.5 4.5-4.5S16 11.5 16 14"
-        stroke="currentColor"
-        strokeWidth="2"
-        strokeLinecap="round"
-      />
-      <circle cx="12" cy="8" r="2" fill="currentColor" />
-    </svg>
+    />
   );
 }