Add a Leaflet example

[StoneTapeStudios]

The arrow-supercluster engine is framework-agnostic — it outputs typed arrays, not deck.gl-specific objects. But the only example currently uses deck.gl, which may give the impression it's deck.gl-only.

A Leaflet example would broaden the audience significantly. Leaflet is the most widely used web mapping library.

What needs to happen

• Create examples/leaflet/ with a minimal Leaflet app that:
  • Loads a GeoParquet file (can reuse the existing synthetic data generator or use a smaller dataset)
  • Uses ArrowClusterEngine directly (not ArrowClusterLayer, which is deck.gl-specific)
  • Renders clusters as Leaflet CircleMarkers or a custom layer
  • Updates clusters on map move/zoom using getClusters()
• Add a section to the arrow-supercluster README mentioning the Leaflet example
• Can be a simple HTML file with a <script type="module"> — doesn't need a build step

References

• Current deck.gl example: examples/basic/
• Engine API: packages/arrow-supercluster/src/arrow-cluster-engine.ts
• Leaflet quick start: https://leafletjs.com/examples/quick-start/