OpenAI shut down dall-e-2 and dall-e-3 on 2026-05-12. Drop their image
generation and edit configs, the Azure dall-e-2 create-and-poll flow, and
the silent dall-e-2 fallback when no model is passed.
image_generation without a model or provider now fails locally with
"model is required". image_edit and image_variation leave model out of
the provider request instead of sending dall-e-2, so providers that
ignore model (Topaz) keep working and OpenAI returns its own 400.