fix(auth): remove unused useSearchParams causing build fail

Next.js 16 prerender error on /auth/callback from
useSearchParams without Suspense. Removed unused import
to fix Docker build.

frontend/src/app/auth/callback/page.tsx

@@ -1,15 +1,14 @@
 "use client";
 
+import { Loader2 } from "lucide-react";
+import { useRouter } from "next/navigation";
 import { useEffect, useState } from "react";
-import { useRouter, useSearchParams } from "next/navigation";
+import { toast } from "sonner";
 import { authApi } from "@/lib/api";
 import { useStore } from "@/lib/store";
-import { Loader2 } from "lucide-react";
-import { toast } from "sonner";
 
 export default function AuthCallbackPage() {
 	const router = useRouter();
-	const searchParams = useSearchParams();
 	const { setUser, setToken } = useStore();
 	const [status, setStatus] = useState("Completing sign in...");
 
@@ -43,7 +42,7 @@ export default function AuthCallbackPage() {
 		};
 
 		handleCallback();
-	}, [searchParams, router, setUser, setToken]);
+	}, [router, setUser, setToken]);
 
 	return (
 		<div className="min-h-screen flex items-center justify-center bg-slate-950 p-4">