Should have an undo button on Editor page

When removing an item or section, we should be able to undo our changes on the Editor page.

Look at the Editor page component to understand how items and sections are currently removed. Research state management to implement an undo stack, likely using a library or custom hook. Define what actions are undoable and how to present the undo UI. Check for existing tests for the Editor to ensure the new feature doesn't break them.

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