Add comprehensive import/export endpoints for:
- Provider and model configuration (with key decryption for export)
- User data and API keys (preserving encrypted data)
Includes merge modes (skip/overwrite/error) for conflict handling,
10MB size limit for imports, and automatic cache invalidation.
Also fix optional field in GlobalModelResponse tiered_pricing.
- Add OFFICIAL_PROVIDERS set to mark first-party vendors in models.dev
- Implement official provider marking function with cache compatibility
- Extend model metadata with family, context_limit, output_limit fields
- Improve frontend model selection UI with wider panel and better search
- Add dark mode support for provider logos
- Optimize scrollbar styling for model lists
- Update deployment documentation with clearer migration steps