`image_gen.provider: nous` fronts three gateways; the stored model id now says which
one serves a request (tools/image_generation_managed.py): FAL catalog ids → FAL gateway,
Krea plugin ids → Krea gateway, anything else → the Nous Portal image plugin. Before,
a Portal model id under the managed selection fell through to FAL, which warned about
an unknown model and billed a FLUX default instead.
The same module builds the managed row's union catalog with each model listed once
(FAL wins identical/cross-id duplicates; Krea 2 appears natively, never as the FAL or
Portal copy), so the picker and the runtime agree on one mapping.
