fix: edit tool error after undo

[AdiY00]

Prevents unnecessary read/write cycles when editing files after undo / redo. From edit -> error "modified externally" -> read -> edit (extra read and edit in context + extra time) to just edit.

• Update FileTime for reverted files in revert() and unrevert() so the edit tool sees them as freshly read rather than externally modified

*Restoring the old read time would be more semantically correct but adds complexity without functional benefit.