fix: Wrap useSearchParams in Suspense boundary for board page

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/app/board/page.tsx

@@ -1,6 +1,6 @@
 'use client';
 
-import { useState, useEffect } from 'react';
+import { useState, useEffect, Suspense } from 'react';
 import { useRouter, useSearchParams } from 'next/navigation';
 import Link from 'next/link';
 import { boardApi, BoardPostListItem, BoardCategory, BoardPostListResponse, BoardCategoryListResponse } from '@/lib/api';
@@ -8,7 +8,7 @@ import { useAuthStore } from '@/lib/store';
 import { useTranslate } from '@/lib/useTranslate';
 import { useLanguageStore } from '@/lib/i18n';
 
-export default function BoardPage() {
+function BoardPageContent() {
   const router = useRouter();
   const searchParams = useSearchParams();
   const { user, token } = useAuthStore();
@@ -294,3 +294,15 @@ export default function BoardPage() {
     </div>
   );
 }
+
+export default function BoardPage() {
+  return (
+    <Suspense fallback={
+      <div className="min-h-screen bg-gray-50 flex items-center justify-center">
+        <div className="inline-block animate-spin rounded-full h-8 w-8 border-4 border-blue-600 border-t-transparent"></div>
+      </div>
+    }>
+      <BoardPageContent />
+    </Suspense>
+  );
+}