Build a Nested Checkboxes component in React with parent-child selection logic.

Requirements:

1. Render a hierarchical structure of checkboxes.
2. Selecting a parent checkbox should:
   • Select/deselect all its child checkboxes.
3. Selecting/deselecting a child should:
   • Update the parent to checked if all children are checked.
   • Update the parent to unchecked if no children are checked.
   • Update the parent to indeterminate if some children are checked.
4. Indent children visually under their parent.
5. Focus on functionality over styling.
6. The component should work out-of-the-box in a live React preview (e.g., CodeSandbox/Sandpack).