refactor: consolidate custom widget admin routes

apps/nextjs/src/app/api/custom-widgets/admin.ts

@@ -2,10 +2,14 @@ import { NextResponse } from "next/server";
 
 import { auth } from "@homarr/auth/next";
 
-export const requireCustomWidgetAdmin = async (): Promise<NextResponse | null> => {
-  const session = await auth();
-  if (!session?.user.permissions.includes("admin")) {
-    return NextResponse.json({ error: "Administrator access is required." }, { status: 403 });
-  }
-  return null;
-};
+type RouteHandler<Arguments extends unknown[]> = (...args: Arguments) => Response | Promise<Response>;
+
+export const adminRoute =
+  <Arguments extends unknown[]>(handler: RouteHandler<Arguments>) =>
+  async (...args: Arguments): Promise<Response> => {
+    const session = await auth();
+    if (!session?.user.permissions.includes("admin")) {
+      return NextResponse.json({ error: "Administrator access is required." }, { status: 403 });
+    }
+    return handler(...args);
+  };