680bd682c7
Previously, Prometheus always used params.currentModel (UI-selected model) when no explicit configuration existed. This bypassed the intended fallback chain (claude-opus-4-6 → gpt-5.4 → glm-5 → gemini-3.1-pro). Now, the UI-selected model is only used if it matches one of the models in Prometheus's fallback chain. Otherwise, the fallback chain resolution takes over and finds an available model. Fixes #2986