Fix attribution (#561)

This adds a `custom_attribution` property to the `Map` class and fix
Maplibre CSS by adding an import. Contributes to:

- #436
- #545

lonboard/_map.py

@@ -167,6 +167,44 @@ def __init__(
       [`lonboard.basemap.CartoBasemap.PositronNoLabels`][lonboard.basemap.CartoBasemap.PositronNoLabels]
     """
 
+    custom_attribution = traitlets.Union(
+        [
+            traitlets.Unicode(allow_none=True),
+            traitlets.List(traitlets.Unicode(allow_none=False)),
+        ]
+    ).tag(sync=True)
+    """
+    Custom attribution to display on the map.
+
+    This attribute supports the same format as the `attribution` property in the
+    Maplibre API.
+
+    - Type: `str` or `List[str]`
+    - Default: `None`
+
+    You can provide either a single string or a list of strings for custom attributions.
+    If an attribution value is set in the map style, it will be displayed in addition to
+    this custom attribution.
+
+    **Example:**
+
+        ```py
+        m = Map(
+            layers,
+            custom_attribution="Development Seed"
+        )
+        ```
+
+    **Example:**
+
+        ```py
+        m = Map(
+            layers,
+            custom_attribution=["Development Seed", "OpenStreetMap"]
+        )
+        ```
+    """
+
     # TODO: We'd prefer a "Strict union of bool and float" but that doesn't
     # work here because `Union[bool, float]` would coerce `1` to `True`, which we don't
     # want, and `Union[float, bool]` would coerce `True` to `1`, which we also don't

src/index.tsx

@@ -14,6 +14,7 @@ import { v4 as uuidv4 } from "uuid";
 import { Message } from "./types.js";
 import { flyTo } from "./actions/fly-to.js";
 import { useViewStateDebounced } from "./state";
+import "maplibre-gl/dist/maplibre-gl.css";
 
 await initParquetWasm();
 
@@ -71,6 +72,7 @@ function App() {
   let [pickingRadius] = useModelState<number>("picking_radius");
   let [useDevicePixels] = useModelState<number | boolean>("use_device_pixels");
   let [parameters] = useModelState<object>("parameters");
+  let [customAttribution] = useModelState<string>("custom_attribution");
 
   // initialViewState is the value of view_state on the Python side. This is
   // called `initial` here because it gets passed in to deck's
@@ -184,7 +186,10 @@ function App() {
         }}
         parameters={parameters || {}}
       >
-        <Map mapStyle={mapStyle || DEFAULT_MAP_STYLE} />
+        <Map
+          mapStyle={mapStyle || DEFAULT_MAP_STYLE}
+          customAttribution={customAttribution}
+        ></Map>
       </DeckGL>
     </div>
   );

src/model/base-layer.ts

@@ -62,8 +62,6 @@ export abstract class BaseLayerModel extends BaseModel {
   }
 
   baseLayerProps(): LayerProps {
-    // console.log("extensions", this.extensionInstances());
-    // console.log("extensionprops", this.extensionProps());
     return {
       extensions: this.extensionInstances(),
       ...this.extensionProps(),