fix: use full-color brand PNGs for login dialog and sidebar

The SVG uses fill=currentColor (inherits text color). Switch to the
full-color PNG brand icons: 192px for login dialog, 48px for sidebar.

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

ui/src/components/LayoutShell.tsx

@@ -625,7 +625,7 @@ function LayoutContent() {
 
   // --- Render -------------------------------------------------------
   const camelLogo = (
-    <img src={`${config.basePath}camel-logo.svg`} alt="" style={{ width: 28, height: 24 }} />
+    <img src={`${config.basePath}cameleer3-logo-48.png`} alt="" style={{ width: 28, height: 28 }} />
   );
 
   const sidebarElement = (