Feature: Dry run for `rename all functions`

`rename_all_functions` currently replaces function names when called. It would be nice to have a sanity check option to do a dry-run.

Expected behavior:
- In: Call `rename_all_functions --dry-run` or something similar
- Out: return a list of candidate names and let the user decide which ones to implement

Start by locating the `rename_all_functions` entry point and checking how its current replacement behavior is exposed. Exercise the command with a dry-run option and verify that it returns candidate names without applying changes, leaving the user to decide which names to implement.

Written by the indexing model from the issue text.