name duplicates

There are many executables named `codegpt` for all possible ends via ChatGPT.
How about the more specific `CommitGPT` (surely also taken, but likely less often).

The issue names no files, tests, or entry points. First inspect the repository for executable, package, documentation, and release-name references, then determine whether renaming them consistently is in scope. Done means the maintainers approve the new name and all agreed project references use it without breaking the CLI.

Written by the indexing model from the issue text.