Execute the existing Wave case-runner CLI tests in Python CI

## Coverage gap

`tools/test_run_tests.py` contains four existing tests for help behavior and compiler discovery, introduced for #537. None of the current workflow commands or contributor verification commands includes `tools.test_run_tests`.

The [Windows amd64 Python CI step](https://github.com/wavefnd/Wave/actions/runs/34583004824/job/103210688441) reports **29 tests** with `tools.test_case_manifest tools.test_test_contracts tools.test_process_tree`. The native Windows crash-code test is included there, but all four case-runner CLI tests are omitted. A local invocation including the missing module runs its four tests successfully.

Sources: [CLI tests](https://github.com/wavefnd/Wave/blob/ed149e7553c06efc30b5167920cc301563d6afb3/tools/test_run_tests.py), [Python CI command](https://github.com/wavefnd/Wave/blob/ed149e7553c06efc30b5167920cc301563d6afb3/.github/workflows/rust.yml#L772), [contributor commands](https://github.com/wavefnd/Wave/blob/ed149e7553c06efc30b5167920cc301563d6afb3/CONTRIBUTING.md#L95).

## Small contribution

- [ ] Add `tools.test_run_tests` to the existing applicable Python CI invocations and contributor verification command.
- [ ] Include the file in Python syntax validation where the other test modules are listed.
- [ ] Verify a nonzero test count for this module on Linux and Windows.
- [ ] Keep the four existing tests and do not add an unrelated runner redesign or new matrix.

This is a CI wiring task, separate from #487's Rust frontend coverage and #499's missing MSVC discovery paths.

Start with tools/test_run_tests.py, then inspect the Python CI command in .github/workflows/rust.yml and the contributor verification command in CONTRIBUTING.md. Add the existing module to the applicable CI, contributor, and Python syntax-validation invocations; done means the module reports a nonzero test count on Linux and Windows while its four tests remain unchanged.

Written by the indexing model from the issue text.