fix(cli): normalize invalid timeout parse errors

[kuishou68]

Summary

• convert non-numeric --timeout inputs into ArgumentTypeError instead of leaking a raw ValueError
• keep the existing positive-number validation message unchanged
• add a CLI regression test covering invalid timeout values

Notes

• I couldn't run the Python test suite in this sandbox because there is no usable python3 / pytest runtime available here.
• The change is intentionally small and only touches timeout argument validation plus the focused regression test.

Closes #2866