feat: implement auth flow and app initialization

src/guards/AuthGuard.tsx

@@ -0,0 +1,30 @@
+'use client';
+
+import { useAppStore } from '@/store/app.store';
+import { useAuthStore } from '@/store/auth.store';
+import { ROUTES } from '@/utils/routes';
+import { useRouter } from 'next/navigation';
+import type { ReactNode } from 'react';
+import { useEffect } from 'react';
+
+export function AuthGuard({ children }: { children: ReactNode }) {
+  const router = useRouter();
+  const accessToken = useAuthStore((state) => state.accessToken);
+  const isInitialized = useAppStore((state) => state.isInitialized);
+  const user = useAppStore((state) => state.user);
+
+  useEffect(() => {
+    if (!isInitialized) return;
+
+    if (!accessToken) {
+      console.debug('[auth] guard:redirect-login');
+      router.replace(ROUTES.LOGIN);
+    }
+  }, [accessToken, isInitialized, router]);
+
+  if (!isInitialized || !accessToken || !user) {
+    return null;
+  }
+
+  return children;
+}