✨ Restore Cursor and Scroll Position on Undo/Redo

[austincondiff]

Description

When performing an undo or redo, the cursor and scroll position should return to the state they were in at the time of the change. Currently, only the text content is restored, but the selection and scroll position are not preserved, which can disrupt the editing experience—especially during rapid or successive edits.

Expected Behavior

• When a change is undone, the insertion point and scroll position should move to where they were when the change originally occurred.
• When a change is redone, the insertion point and scroll position should likewise be restored to their prior state.
• This behavior should feel seamless and natural, mirroring the expectations of professional editors on macOS.

Proposed Implementation

• Extend the existing Mutation or UndoGroup struct to include the selected range and visible scroll rect at the time of the change.
• Capture these properties during registerMutation(_:).
• Restore the stored selected range and scroll rect in undo() and redo() methods after applying the text mutations.

Benefits

• Improves consistency and usability of the editor during undo/redo workflows.
• Reduces disorientation from insertion point jumps or loss of context.
• Brings CodeEditTextView in line with native Mac editor expectations.

Additional Notes

• Consider edge cases such as when the associated text range no longer exists.