Implement visualization for syntax trees

[jwalsh]

Create a visualization component for the syntax trees that can display the AST structure graphically. This would make it easier to understand and debug the syntax parsing results.

Features should include:

• Interactive tree view with expand/collapse functionality
• Visual highlighting of node types (NP, VP, S, etc.)
• Metadata inspection on hover/click
• Export options for SVG/PNG for documentation
• Integration with the existing proust_reader output

Possible implementation approaches:

1. Web-based visualization using D3.js (mentioned in CLAUDE.md)
2. Terminal-based tree visualization for command-line usage
3. Integration with VS Code or Emacs for in-editor visualization

This will significantly improve the developer experience and make the tool more useful for linguistic analysis.