Improve how we format generated code

We use pre-commit to format generated code as part of code generation CI.

However, this is a bit awkward. We can't use pre-commit.ci to update these versions because it seems to break the state of the repo (see #850).

We should consider if we can use Python code formatting tools directly, possibly as part of the generated library.

Start by reviewing the generated-code CI and its pre-commit configuration, then read issue #850 to understand the repository-state failure. Compare the current workflow with the possible Python formatting-tool approach; done requires a clear, working formatting process for generated code without the reported state breakage.

Written by the indexing model from the issue text.