build_nep_traj is unusable: --test-ratio divides by zero and write_from_trajectory misplaces its arguments

[galjos]

Two independent bugs, each fatal:

NEPWriter("out.xyz").write_from_files(["md"], test_ratio=0.25)
# ZeroDivisionError: float division by zero        (nep_writer.py:472)
NEPWriter("o.xyz").write_from_trajectory(traj)
# PQTypeError: Argument 'file' ... but got <class 'bool'>   (nep_writer.py:818)

The splitting setup only derives ratios from total_ratios and never uses test_ratio; the trajectory path omits the file argument so use_forces lands in the file slot.