feat(mapillary): street-level layer core — coverage, sequences, viewer bridge, query engine

Camera-driven Mapillary coverage (z0–5 overview points from orbit, z11–14
ground-clamped sequence lines below 60 km), per-sequence image cones, an
embedded MapillaryJS viewer bridge with a camera-follow mode, sprite icons
for map features, and a query engine that turns a plan into a streamed
z14 tile fan-out. Registers an on-globe CC BY-SA 4.0 credit while enabled.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

src/standalone/layerSources.js

@@ -13,6 +13,7 @@ import { createSatelliteSource } from '../layers/satellites/source.js';
 import { createLaunchSource } from '../layers/launches/source.js';
 import { createOverpassAlprSource } from '../layers/alpr/source.js';
 import { createFirmsSource } from '../layers/firms/source.js';
+import { createMapillarySource } from '../layers/mapillary/source.js';
 import { createReferenceSources } from '../sources/reference.js';
 export { createReferenceSources as createStandaloneReferenceSources } from '../sources/reference.js';
 
@@ -35,5 +36,8 @@ export function createStandaloneLayerSources() {
     launches: createLaunchSource(),
     alpr: createOverpassAlprSource(),
     firms: createFirmsSource(),
+    mapillary: createMapillarySource({
+      token: import.meta.env?.MAPILLARY_CLIENT_TOKEN || '',
+    }),
   };
 }