fix AI-419
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## Summary by CodeRabbit
- New Features
- New API to fetch available models for a prompt, returning default,
optional, and pro models with human‑readable names.
- Added temperature and topP settings to prompt configuration for finer
control.
- Refactor
- When no model is chosen, the default model is used instead of
auto-picking a pro model.
- Model metadata across providers now includes readable names, improving
listings and selection UX.
- Tests
- Updated test snapshots and descriptions to reflect the new
default-model behavior.
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