Modal Lifecycle

Write createModal() that RETURNS an object with: - open(trigger, root) — marks the modal open, remembers trigger as the element to restore focus to later, stores root as the modal content, and returns "opened" - close() — marks it closed and returns "closed"; if it was not open, returns "already-closed" - restoreFocus() — returns and clears the remembered trigger (undefined if none) - isOpen() — boolean state Opening twice without closing returns "already-open" and must NOT overwrite the remembered trigger.

Difficulty: intermediate