Fix notebook widget cloud provider field visibility

- Add separate VBox containers for each cloud provider
- Show only relevant provider fields based on cluster type selection
- Add HuggingFace Spaces integration to cluster type dropdown
- Implement dynamic field population for all cloud providers
- Add cloud provider default configurations
- Update load/save methods to handle all cloud provider fields
- Fix widget UI to show proper provider-specific options

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: jeremymanning