Extend nearest-polygon fallback to all countries, not just Scotland

Points in the sea near England (or any other country) now fall back to
Polygon.nearest() to find the closest admin_level>=7 polygon on land,
giving a specific civil parish or district instead of just returning
England (Q21).

Closes #30

lookup.py

@@ -151,6 +151,13 @@ def lat_lon_to_wikidata(
                 if not nearby_result.get("missing"):
                     return {"elements": elements, "result": nearby_result}
 
+    # For points in the sea near any coast (e.g. England), try nearest polygon
+    nearest = model.Polygon.nearest(lat, lon)
+    if nearest:
+        nearby_result = do_lookup([nearest], lat, lon)
+        if not nearby_result.get("missing"):
+            return {"elements": elements, "result": nearby_result}
+
     if not needs_commons:
         # Direct lookup: find Wikidata items whose P402 (OSM relation ID) matches
         # one of the OSM polygons that contain this point.