Extends the interactive history substitution function to support an
optional third field `old/new/index`.
- Keeps default behavior of targeting the most recent command (index 1).
- Allows targeting a specific history entry by appending a number.
- Validates that the index is a positive integer before attempting retrieval.
- Safely handles cases where the requested history index does not exist.
Example: 'cat/bat/5' now replaces 'cat' with 'bat' in the 5th previous command.
rootiest
