Add right-click context menu and "..." dropdown button for folders in
the file tree, enabling file operations within any folder:
- New File: Create empty file via Blob upload
- New Folder: Create subfolder
- Upload File: Upload multiple files to folder
- Upload Folder: Upload entire folder structure preserving hierarchy
Implementation includes:
- FileOperationsMenu: Shared menu component for both triggers
- FileTreeContextMenu: Right-click menu with absolute positioning
- FileTreeNode: Added context menu and dropdown button for folders
- Store slice for context menu state management
- i18n strings for en-US and zh-Hans
- Replace useRef pattern with useMemo for store creation in context.tsx
- Remove unused extension prop from EditorTabItem
- Fix useMemo dependency warnings in editor-tabs.tsx and skill-doc-editor.tsx
- Add proper OnMount type for Monaco editor instead of any
- Delete unused file-item.tsx and fold-item.tsx components
- Remove unused getExtension and fromOpensObject utilities from type.ts
- Refactor auto-reveal effect in files.tsx for better readability
Implement MVP features for skill editor based on design doc:
- Add Zustand store with Tab, FileTree, and Dirty slices
- Rewrite file tree using react-arborist for virtual scrolling
- Implement Tab↔FileTree sync with auto-reveal on tab activation
- Add upload functionality (new folder, upload file)
- Implement Monaco editor with dirty state tracking and Ctrl+S save
- Add i18n translations (en-US and zh-Hans)
