Undo / Redo Manager

Requirements

• Export UndoRedoManager as named and default. Its constructor accepts an initial value. Expose read-only value, canUndo, and canRedo getters.
• set(value) commits a new value and discards the redo branch. undo() moves back one commit; redo() moves forward one commit. All three methods return the current value after the operation.
• At either history boundary undo or redo is a no-op. If Object.is(value, currentValue) is true, set is a no-op and must preserve any redo branch.
• reset(value) replaces all history with that value, leaving canUndo and canRedo false. It returns the current value.
• Store values by reference without cloning. Each manager is independent. Mutating an object is not a new commit; set a new object when you need a distinct snapshot. History limits and persistence are outside scope.

Examples

Input: const history = new UndoRedoManager("A");
history.set("B");
history.set("C");
history.undo();
history.redo();
Output: undo returns "B"; redo returns "C".

Input: history.undo();
history.set("D");
history.redo();
Output: The old "C" branch is discarded; redo returns "D".