feat: Advanced file editor and file tree improvements (#444)

# Features
- File drag and drop upload: Support uploading files and folders via drag and drop
- Binary file handling: Detect binary files and display a friendly message instead of trying to edit them
- Folder download: Download folders as ZIP files (using JSZip library)
- Context menu integration: Full right-click context menu for file operations (rename, delete, copy path, download, new file/folder)

src/components/file-tree/hooks/useExpandedDirectories.ts

@@ -4,6 +4,7 @@ type UseExpandedDirectoriesResult = {
   expandedDirs: Set<string>;
   toggleDirectory: (path: string) => void;
   expandDirectories: (paths: string[]) => void;
+  collapseAll: () => void;
 };
 
 export function useExpandedDirectories(): UseExpandedDirectoriesResult {
@@ -35,10 +36,15 @@ export function useExpandedDirectories(): UseExpandedDirectoriesResult {
     });
   }, []);
 
+  const collapseAll = useCallback(() => {
+    setExpandedDirs(new Set());
+  }, []);
+
   return {
     expandedDirs,
     toggleDirectory,
     expandDirectories,
+    collapseAll,
   };
 }