feat: wire favicon icons into Next.js metadata

Light/dark adaptive 32x32 PNG icons + SVG icon + apple-touch-icon
registered in metadata so browsers pick them up automatically.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/layout.tsx

@@ -33,6 +33,14 @@ export const metadata: Metadata = {
     index: true,
     follow: true,
   },
+  icons: {
+    icon: [
+      { url: "/icon-light-32x32.png", sizes: "32x32", type: "image/png", media: "(prefers-color-scheme: light)" },
+      { url: "/icon-dark-32x32.png", sizes: "32x32", type: "image/png", media: "(prefers-color-scheme: dark)" },
+      { url: "/icon.svg", type: "image/svg+xml" },
+    ],
+    apple: "/apple-icon.png",
+  },
 };
 
 export default function RootLayout({ children }: Readonly<{ children: React.ReactNode }>) {