feat: optimize vision tools and image handling

- Add model-aware vision tool loading based on supports_vision flag
- Move view_image_tool from config to builtin tools for dynamic inclusion
- Add timeout to image search to prevent hanging requests
- Optimize image search results format using thumbnails
- Add image validation for reference images in generation
- Improve error handling with detailed messages

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>