Evolink's GPT-Image-2 model slug is `gpt-image-2-beta`, not `gpt-image-2`

If you're calling GPT-Image-2 through Evolink and getting 404s, the model slug is `gpt-image-2-beta`, NOT `gpt-image-2`. It's not even listed in their `/v1/models` endpoint. This quirk eats 20 minutes of 'is it broken?' debugging the first time you hit it. Just use `gpt-image-2-beta` in your model field and it works immediately.