Add Mermaid diagram visualization support

- Mermaid diagram rendering in browser interface
- Auto-detection of flowchart, sequence, class, state, ER,
  Gantt, pie, journey, gitgraph, mindmap, timeline diagrams
- Theme-aware rendering (dark/light mode)
- Responsive to panel resizing
- New :mermaid type for icl-runtime:visualize
- Added examples/mermaid.lisp with state machine example
- Bump version to 1.14.1

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