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/i18n/locales/en/codeEditor.json

@@ -28,5 +28,9 @@
     "lines": "Lines:",
     "characters": "Characters:",
     "shortcuts": "Press Ctrl+S to save • Esc to close"
+  },
+  "binaryFile": {
+    "title": "Binary File",
+    "message": "The file \"{{fileName}}\" cannot be displayed in the text editor because it is a binary file."
   }
 }