Follow-up for #3171 cherry-pick — the contributor's validation block
called get_provider_credentials() which doesn't exist on current main.
Replaces it with get_auth_status() limited to API-key providers in
PROVIDER_REGISTRY so providers without a registry entry (openrouter,
anthropic, custom) don't trigger false 'not authenticated' failures.
Also runs the provider name through resolve_provider() so aliases like
'glm'/'moonshot' validate correctly.
Adds StefanIsMe to AUTHOR_MAP.
93f9db59b2