Enhance LivePreview to Support Mermaid Diagrams

To further unify the developer experience within the Portal and Documentation apps, we should extend the Neo.component.code.LivePreview component to support Mermaid diagrams.

Current State: LivePreview expects JavaScript code that exports a Neo.mjs component or VDOM, which it then executes and mounts in the preview area.

New Capability: Enable LivePreview to accept Mermaid diagram syntax.

Implementation Strategy:

1. Detection/Configuration: Add a mechanism to determine if the content is Mermaid code (e.g., a language config or auto-detection).
2. Renderer Switching:
   • If JavaScript: Keep existing execution logic.
   • If Mermaid: Instantiate Neo.component.wrapper.Mermaid in the preview container and bind its value to the editor content.
3. Editor Integration: Ensure the Monaco Editor uses the correct syntax highlighting for Mermaid.

Benefits:

• Unified "Playground" for both UI widgets and architectural diagrams.
• Simplifies documentation authoring (one component for all live examples).