feat: add ScatterMap trace for the MapLibre map subplot (#417)

Add `ScatterMap`, the MapLibre-based counterpart to `ScatterMapbox`, drawn
on the `layout.map` subplot (`LayoutMap`/`MapStyle`). 
It mirrors`ScatterMapbox` field-for-field - markers/lines, `Fill`/`Selection`, and the
full hover set (text/hovertext/hoverinfo/hovertemplate/customdata/hoverlabel), 
but emits `"type": "scattermap"` and references `layout.map`.

Add a `PlotType::ScatterMap` variant, re-export `ScatterMap` and the
`scatter_map` module, and add a `serialize_scatter_map` unit test plus a doc
example.

Signed-off-by: Andrei Gherghescu <8067229+andrei-ng@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: jqnatividad

CHANGELOG.md

@@ -12,6 +12,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) a
 - [[#410](https://github.com/plotly/plotly.rs/pull/410)] Add `LayoutGeo` options: `fitbounds` (`GeoFitBounds`), `resolution` (`GeoResolution`, 1:110M/1:50M base-layer detail), and `bgcolor`
 - [[#412](https://github.com/plotly/plotly.rs/pull/412)] Add `Violin` trace type with box, mean line, KDE span, and split/grouped support
 - [[#414](https://github.com/plotly/plotly.rs/issues/414)] Add `DensityMap` (MapLibre `map` subplot) trace type — density heatmaps with full color-scale and hover support
+- [[#417](https://github.com/plotly/plotly.rs/issues/417)] Add `ScatterMap` (MapLibre `map` subplot) trace type — the modern counterpart to `ScatterMapbox`
 
 ### Changed
 

plotly/src/common/mod.rs

@@ -212,6 +212,7 @@ pub enum PlotType {
     ScatterGL,
     Scatter3D,
     ScatterMapbox,
+    ScatterMap,
     ScatterGeo,
     ScatterPolar,
     ScatterPolarGL,

plotly/src/lib.rs

@@ -61,13 +61,13 @@ pub use plot::{Plot, Trace, Traces};
 // Also provide easy access to modules which contain additional trace-specific types
 pub use traces::{
     box_plot, choropleth, choropleth_map, contour, density_map, heat_map, histogram, image, mesh3d,
-    sankey, scatter, scatter3d, scatter_mapbox, sunburst, surface, treemap, violin,
+    sankey, scatter, scatter3d, scatter_map, scatter_mapbox, sunburst, surface, treemap, violin,
 };
 // Bring the different trace types into the top-level scope
 pub use traces::{
     Bar, BoxPlot, Candlestick, Choropleth, ChoroplethMap, Contour, DensityMap, DensityMapbox,
     HeatMap, Histogram, Image, Mesh3D, Ohlc, Pie, Sankey, Scatter, Scatter3D, ScatterGeo,
-    ScatterMapbox, ScatterPolar, Sunburst, Surface, Table, Treemap, Violin,
+    ScatterMap, ScatterMapbox, ScatterPolar, Sunburst, Surface, Table, Treemap, Violin,
 };
 
 pub trait Restyle: serde::Serialize {}

plotly/src/traces/mod.rs

@@ -18,6 +18,7 @@ pub mod sankey;
 pub mod scatter;
 pub mod scatter3d;
 pub mod scatter_geo;
+pub mod scatter_map;
 pub mod scatter_mapbox;
 mod scatter_polar;
 pub mod sunburst;
@@ -43,6 +44,7 @@ pub use sankey::Sankey;
 pub use scatter::Scatter;
 pub use scatter3d::Scatter3D;
 pub use scatter_geo::ScatterGeo;
+pub use scatter_map::ScatterMap;
 pub use scatter_mapbox::ScatterMapbox;
 pub use scatter_polar::ScatterPolar;
 pub use sunburst::Sunburst;