get_config_options() -> tuple[ConfigOption, ...]Return every option, credentials-first then by domain group.
Cached: provider credentials are generated once from PROVIDER_API_KEY_ENV
on first call (which lazily imports model_config). The cache assumes that
registry is an immutable module constant; a test that monkeypatches it must
call get_config_options.cache_clear() (and _options_by_key.cache_clear()).