Implement provider preference feature for OpenRouter models:
1. Database Schema:
- Add ModelProviderPreferenceTable to store provider preferences per model
2. Console Core API:
- Add ProviderPreferenceSchema for validation
- Add setProviderPreference(), getProviderPreference(), deleteProviderPreference(), and listProviderPreferences() functions
3. Request Handler:
- Modify handler.ts to fetch provider preferences from database
- Pass provider preferences to OpenRouter in request body
4. Admin UI:
- Add provider preference dropdown for OpenRouter models in model-section.tsx
- Add 'Allow fallbacks' checkbox for fallback control
- Add corresponding CSS styles
5. CLI Config:
- Add providerPreference field to Provider model config schema
- Support configuring provider preferences via opencode.json
6. Provider SDK:
- Inject provider preferences into OpenRouter request body in fetch wrapper
This allows workspace admins to specify preferred providers for OpenRouter
models, ensuring models like Claude route through specific providers
(e.g., Anthropic direct) rather than third-party providers.
