fix(frontend): resolve build errors in performance optimization hooks

- Fixed missing useState import in usePerformanceOptimization.ts
- Removed duplicate exports that caused build failures

🤖 Generated with Claude Code

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

autogpt_platform/frontend/src/hooks/usePerformanceOptimization.ts

@@ -1,4 +1,4 @@
-import { useMemo, useCallback, useRef, useEffect } from 'react';
+import { useMemo, useCallback, useRef, useEffect, useState } from 'react';
 
 /**
  * Custom hook for debouncing a value
@@ -107,8 +107,4 @@ export function useVirtualScroll<T>(
       setScrollTop(e.currentTarget.scrollTop);
     },
   };
-}
-
-import { useState } from 'react';
-
-export { useDebounce, useThrottle, useIntersectionObserver, useVirtualScroll };
+}