feat: enhance file description endpoint with security and error handling improvements

- Implemented path validation against ALLOWED_ROOT_DIRECTORY to prevent arbitrary file reads and prompt injection attacks.
- Added error handling for file reading, including specific responses for forbidden paths and file not found scenarios.
- Updated the description generation logic to truncate large files and provide structured prompts for analysis.
- Enhanced logging for better traceability of file access and errors.

These changes aim to improve the security and reliability of the file description functionality.

apps/ui/src/components/views/agent-view.tsx

@@ -33,6 +33,7 @@ import {
   isImageFile,
   fileToText,
   getTextFileMimeType,
+  formatFileSize,
   DEFAULT_MAX_FILE_SIZE,
   DEFAULT_MAX_FILES,
 } from '@/lib/image-utils';
@@ -942,12 +943,3 @@ export function AgentView() {
     </div>
   );
 }
-
-// Helper function to format file size
-function formatFileSize(bytes: number): string {
-  if (bytes === 0) return '0 B';
-  const k = 1024;
-  const sizes = ['B', 'KB', 'MB', 'GB'];
-  const i = Math.floor(Math.log(bytes) / Math.log(k));
-  return parseFloat((bytes / Math.pow(k, i)).toFixed(1)) + ' ' + sizes[i];
-}