feat(bikeshare): add Barcelona's Bicing and AMBici

- Bicing (543 stations, PBSC) and AMBici (237 e-bike stations across the
  metropolitan area, nextbike) join the GBFS registry from the operators'
  keyless GBFS 2.3 feeds, both listed in MobilityData's systems catalogue.
- gbfs.nextbike.net joins the proxy allowlist as an exact host.
- Credits, DATA_SOURCES, CURRENT-STATE and CHANGELOG updated; a test pins
  each system's proxy reachability and the range check for its outermost
  stations.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/layers/bikeshare/registry.js

@@ -554,6 +554,32 @@ const RAW_GBFS_CITY_REGISTRY = [
       'https://api.cyclocity.fr/contracts/lillestrom/gbfs/station_status.json',
     provider: 'Bysykkel Lillestrøm',
   },
+  {
+    id: 'barcelona-bicing',
+    city: 'Barcelona, Spain',
+    centerLat: 41.3926,
+    centerLon: 2.164,
+    loadRadiusKm: 40,
+    stationInformationUrl:
+      'https://barcelona.publicbikesystem.net/customer/gbfs/v2/en/station_information.json',
+    stationStatusUrl:
+      'https://barcelona.publicbikesystem.net/customer/gbfs/v2/en/station_status.json',
+    provider: 'Bicing',
+  },
+  // AMBici covers the metropolitan municipalities around Barcelona, from
+  // Castelldefels to Badalona, and overlaps Bicing only at the city edge.
+  {
+    id: 'barcelona-ambici',
+    city: 'Barcelona metropolitan area, Spain',
+    centerLat: 41.37,
+    centerLon: 2.07,
+    loadRadiusKm: 40,
+    stationInformationUrl:
+      'https://gbfs.nextbike.net/maps/gbfs/v2/nextbike_bs/en/station_information.json',
+    stationStatusUrl:
+      'https://gbfs.nextbike.net/maps/gbfs/v2/nextbike_bs/en/station_status.json',
+    provider: 'AMBici',
+  },
 ];
 function normalizeRegistryEntry(entry) {
   const id = String(entry?.id || '')