fix admin pages accessible by non admin users (#2988)

Co-authored-by: Michael Genson <71845777+michael-genson@users.noreply.github.com>

frontend/middleware/admin-only.ts

@@ -0,0 +1,10 @@
+interface AuthRedirectParams {
+    $auth: any
+    redirect: (path: string) => void
+}
+export default function ({ $auth, redirect }: AuthRedirectParams) {
+    // If the user is not an admin redirect to the home page
+    if (!$auth.user.admin) {
+        return redirect("/")
+    }
+}