- Add constants.ts with ROOT_ID, CONTEXT_MENU_TYPE, NODE_MENU_TYPE
- Add root utilities to tree-utils.ts (isRootId, toApiParentId, etc.)
- Replace '__root__' with ROOT_ID for consistent root identifier
- Replace inline 'blank'/'root' strings with constants
- Use NodeMenuType for type-safe menu type props
- Remove duplicate ContextMenuType from types.ts, use from constants.ts
- Extract useFileOperations hook to hooks/use-file-operations.ts
- Move tree utilities to utils/tree-utils.ts
- Move file utilities to utils/file-utils.ts (renamed from utils.ts)
- Remove unnecessary JSDoc comments throughout components
- Simplify type.ts to only contain local type definitions
- Clean up store/index.ts by removing verbose comments