Add RTL (Right-to-Left) text plugin support

[yharby]

Summary

Add support for the MapLibre RTL text plugin to enable proper rendering of right-to-left languages like Arabic and Hebrew.

Problem

Currently, maps with Arabic or Hebrew labels render incorrectly - characters appear disconnected or in reverse order.

Solution

Bundle the @mapbox/mapbox-gl-rtl-text plugin with the package and automatically initialize it for all maps. This provides:

• Offline support: Plugin is bundled, no CDN dependency
• Zero configuration: Works automatically, no API changes needed
• Lazy loading: Plugin only activates when RTL text is encountered

Implementation

1. Bundle mapbox-gl-rtl-text.js in maplibre/srcjs/
2. Patch pywidget.js to expose maplibregl globally
3. Modify to_html() to inject RTL plugin as blob URL before map initialization
4. Call maplibregl.setRTLTextPlugin(blobUrl, true) before pymaplibregl(data)

Scope

This PR adds RTL support for standalone HTML rendering (Map.to_html() and Map.save()).
Shiny/Jupyter widget paths may require changes to the maplibre-bindings repo.

[yharby]

Scope Clarification

This implementation adds RTL support for standalone HTML rendering only (Map.to_html() and Map.save()).

What works:

• ✅ Map.to_html() - RTL text renders correctly
• ✅ Map.save() - RTL text renders correctly

What needs additional work (in maplibre-bindings repo):

• ❌ Jupyter notebooks (via MapWidget)
• ❌ Marimo notebooks
• ❌ Shiny apps

To add RTL support for Jupyter/Marimo/Shiny, the ipywidget.js bundle in the maplibre-bindings repo would need similar modifications:

1. Bundle the RTL plugin
2. Call setRTLTextPlugin() before map creation

This could be tracked as a separate issue in the maplibre-bindings repo.

[yharby]

PR submitted: #159