fix favicon delivery and cache invalidation

app/favicon.ico/route.ts

@@ -0,0 +1,20 @@
+import { NextResponse } from "next/server";
+
+import { buildFallbackIconResponse, getDynamicSiteIconUrls } from "@/lib/site-icons";
+
+export const dynamic = "force-dynamic";
+export const revalidate = 0;
+
+export async function GET() {
+  const iconUrls = await getDynamicSiteIconUrls();
+
+  if (iconUrls.faviconAssetUrl) {
+    const response = NextResponse.redirect(iconUrls.faviconAssetUrl, 307);
+
+    response.headers.set("Cache-Control", "no-store, max-age=0");
+
+    return response;
+  }
+
+  return buildFallbackIconResponse(iconUrls.siteName, 32);
+}