Fix empty --password handling in CLI option parsing

[srichs]

Motivation

• _get_password previously caught all ValueErrors and treated an explicitly empty --password//password value as if the option were absent, which masks invalid input.

Description

• Update _get_password to first check for the presence of the password flag and return (None, -1) only when the flag is missing, and to still raise ValueError when the flag is present but has no value, and add test_get_password_empty_value_raises to cover this behavior.

Testing

• Ran pytest -q and the test suite passed: 43 passed.

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Codex Task