feat(calm-explorer): support CALM patterns and nested containers

Add comprehensive support for CALM pattern specification and multi-level container nesting:

Architecture visualization enhancements:
- Expand options relationships to display pattern alternatives (AWS/GCP/Azure)
- Detect and visualize container nodes regardless of declared node-type
- Support multi-level nested containers (e.g., provider > vpc > subnet > tier)
- Build parent-child map for proper hierarchical layout
- Fix layout algorithm to handle nested system nodes correctly

UI improvements:
- Add Enter key support to GitHub Connect dialog for faster workflow
- Fix ResizablePanel resize inversion by adding panel IDs and ordering

This enables visualization of complex CALM patterns like three-tier-web-app with proper nested container hierarchies.

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

Author: pmerrison