fix(loading): forward download_config to LocalEvaluationModuleFactory for local paths

[xodn348]

Summary

evaluation_module_factory has two branches that resolve a local script path — one for a bare .py file and one for a directory containing a same-named script. In both cases the function constructs LocalEvaluationModuleFactory without forwarding the caller-supplied download_config. The factory then falls back to a fresh DownloadConfig(), silently discarding any settings the caller passed (e.g. local_files_only=True, a custom cache_dir, or use_etag=False). This makes it impossible to prevent outbound network requests when loading local evaluation modules in air-gapped or restricted-network environments, because the _download_additional_modules path inside the factory always receives default download behaviour regardless of what the caller specified.

The fix is a one-liner (×2): add download_config=download_config to each LocalEvaluationModuleFactory(...) call at lines 619–621 and 625–627 of src/evaluate/loading.py. The non-local (Hub, cached) branches already pass download_config correctly; this aligns the local branches with them.

Two regression tests are added to tests/test_load.py that verify download_config is forwarded for both the .py-file path and the directory path. They use mock.patch to intercept the factory constructor call and assert the download_config kwarg matches the caller-supplied object.

Issue

Fixes #709

Local verification

# Linters (black 22.12.0, isort, flake8) — matches CI quality job
$ cd /tmp/evaluate
$ python -m black --check --line-length 119 --target-version py36 src/evaluate/loading.py tests/test_load.py
All done! ✨ 🍰 ✨
2 files would be left unchanged.

$ isort --check-only src/evaluate/loading.py tests/test_load.py
(no output — all imports correctly sorted)

$ flake8 src/evaluate/loading.py tests/test_load.py
(no output — no issues)

ALL LINTERS PASS

# Unit tests (non-network, mirrors `python -m pytest -n 2 ./tests/` unit job)
$ PYTHONPATH=/tmp/evaluate/src python -m pytest tests/test_load.py -v \
    -k "not Hub and not hub and not remote"
============================= test session starts ==============================
platform linux -- Python 3.11.15, pytest-9.0.3, pluggy-1.6.0
collecting ... collected 9 items / 5 deselected / 4 selected

tests/test_load.py::ModuleFactoryTest::test_CachedMetricModuleFactory PASSED [ 25%]
tests/test_load.py::ModuleFactoryTest::test_LocalMetricModuleFactory PASSED [ 50%]
tests/test_load.py::ModuleFactoryTest::test_evaluation_module_factory_passes_download_config_local_dir PASSED [ 75%]
tests/test_load.py::ModuleFactoryTest::test_evaluation_module_factory_passes_download_config_local_script PASSED [100%]

======================= 4 passed, 5 deselected in 0.07s ========================
=== LOCAL_TEST_PASSED ===

Risk

The change is minimal — two download_config=download_config keyword arguments added to existing LocalEvaluationModuleFactory constructor calls. The parameter was already defined on the constructor with a safe default (DownloadConfig()), so passing it explicitly cannot break any existing behaviour: callers that previously got the default will now get exactly the same default (since the top-level evaluation_module_factory already initialises download_config = DownloadConfig(**download_kwargs) when none is supplied). The only callers affected are those who explicitly pass a non-default DownloadConfig to evaluation_module_factory with a local path — those callers previously had their config silently dropped; now it is respected.