Make parameterize_extract_columns respect reassign_columns=False

[breken-ai]

@parameterize_extract_columns(..., reassign_columns=False) ignores the flag. expand_node builds the node it passes to @parameterize with callabl=wrapper_fn every time, and parameterize.expand_node calls node_.callable. So the fn_to_call choice never takes effect: the output columns are still renamed by position. Each extracted column can then silently carry another column's data.

@parameterize_extract_columns(
    ParameterizedExtract(("y", "x"), {"k": value(1)}),
    reassign_columns=False,
)
def df(k: int) -> pd.DataFrame:
    return pd.DataFrame({"x": [k], "y": [k * 100]})

dr.execute(["x", "y"])
# on main: x == 100, y == 1  (columns renamed positionally despite reassign_columns=False)
# expected: x == 1, y == 100

If the function returns a different number of columns than outputs, the rename also raises a length-mismatch error, which is the other case reassign_columns=False is meant to allow.

Changes

• hamilton/function_modifiers/expanders.py: build the node from fn_to_call (the renaming wrapper only when reassign_columns=True), so the flag takes effect. The default True path is unchanged.
• tests/function_modifiers/test_expanders.py: test_parameterized_extract_columns_no_reassign_columns.

How I tested this

• New test on unmodified main (661aa888): fails with DataFrame.columns are different ... [left]: ['y', 'x'] [right]: ['x', 'y'].
• With the fix, it passes. The existing test_parameterized_extract_columns (the default path) still passes.
• pytest tests/function_modifiers tests/test_function_modifiers.py tests/test_end_to_end.py tests/test_hamilton_driver.py tests/test_async_driver.py: 528 passed.
• ruff check and ruff format --check (0.15.14) are clean. git diff --check is clean.

Notes

The flag has had no effect since parameterize_extract_columns was added in 72b0a09 (2022-11).

Checklist

• PR has an informative and human-readable title (this will be pulled into the release notes)
• Changes are limited to a single goal (no scope creep)
• Code passed the pre-commit check & code is left cleaner/nicer than when first encountered.
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output) — no new functions
• Placeholder code is flagged / future TODOs are captured in comments — none added
• Project documentation has been updated if adding/changing functionality — no documented behavior changes; this makes the code match the existing docs

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AI disclosure (per the ASF Generative Tooling guidance): this change was written with an AI coding tool (Claude Code, Claude Opus 5.5) working through the breken-ai account. The tool found the bug, wrote the fix and the test, and wrote this description. The commit carries a Generated-by: trailer. The diff is a small original change to existing Hamilton code and includes no third-party material. The red/green runs above are real and can be re-run from the diff. If you would rather not take AI-assisted contributions here, say so and I will close this.