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/ui/layerPanel.js

@@ -28,7 +28,7 @@ const PANEL_GROUPS = [
   },
   {
     label: 'Cameras',
-    ids: ['cctv', 'alpr-cameras'],
+    ids: ['cctv', 'mapillary', 'alpr-cameras'],
   },
   {
     label: 'Infrastructure',
@@ -58,6 +58,7 @@ const PANEL_LABELS = {
   'ais-live-vessels': 'Live Vessels',
   bikeshare: 'Bike Share',
   cctv: 'Cameras',
+  mapillary: 'Street Level (Mapillary)',
   'alpr-cameras': 'Mapped ALPR Cameras',
   'local-datacenters': 'Data Centers',
   'local-firms': 'Active Fires',