- Remove _default_model initialization and attribute
- Remove Django settings fallback for model (lines 89-90)
- Remove model loading from IntegrationSettings in _load_account_settings()
- Update run_ai_request() to require model parameter (not Optional)
- Add model validation at start of run_ai_request()
- Deprecate get_model() method (raises error with helpful message)
- Update error handling to use provided model (no fallback)
- Simplify debug logging (removed model_from_settings comparison)