Build a file explorer tree

• Renders a nested folder and file structure from JSON; folders expand and collapse on click, with a chevron and distinct icons or labels for folders and files
• Folders are sorted before files, each group alphabetically (case-insensitive), at every level
• Add file or folder inside a selected folder using an inline input; names must be non-empty and unique among siblings
• Rename (Enter or double-click, Escape to cancel) and delete (with confirmation for non-empty folders)
• The selected item is highlighted; creating, renaming and deleting update the tree immutably and keep expansion state
• Keyboard navigation: Arrow Up and Down move between visible nodes, Arrow Right expands or enters, Arrow Left collapses or goes to the parent, F2 renames, Delete removes
• Accessible tree roles: role="tree", role="treeitem", aria-expanded, aria-selected

Only after every requirement works.

• Drag and drop to move items between folders
• Filter by name while preserving ancestor folders
• Persist the tree and the expanded folders in localStorage