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/main-content/view/MainContent.tsx

@@ -107,7 +107,7 @@ function MainContent({
       />
 
       <div className="flex-1 flex min-h-0 overflow-hidden">
-        <div className={`flex flex-col min-h-0 min-w-0 overflow-hidden ${editorExpanded ? 'hidden' : ''} flex-1`}>
+        <div className={`flex flex-col min-h-0 min-w-[200px] overflow-hidden ${editorExpanded ? 'hidden' : ''} flex-1`}>
           <div className={`h-full ${activeTab === 'chat' ? 'block' : 'hidden'}`}>
             <ErrorBoundary showDetails>
               <ChatInterface