Return nearest parish/polygon for points in the sea near the coast

When a point falls in the sea within a country boundary (e.g. Scotland
Q22 or England Q21) but not within any specific parish, find the nearest
civil parish or high-admin-level polygon within ~0.15 degrees (~10-17km).

- Add get_nearest_scotland_code() for Scottish civil parishes
- Add Polygon.nearest() for general OSM polygon lookup
- Use .limit(1).scalar() in scotland.py for cleaner returns

lookup.py

@@ -136,6 +136,36 @@ def lat_lon_to_wikidata(lat: float, lon: float) -> dict[str, typing.Any]:
     if admin_level >= 7:
         return {"elements": elements, "result": result}
 
+    # Point is in Scotland but not in a specific parish — try nearest parish
+    if result.get("wikidata") == "Q22":
+        nearby_code = scotland.get_nearest_scotland_code(lat, lon)
+        if nearby_code:
+            rows = wikidata.lookup_scottish_parish_in_wikidata(nearby_code)
+            add_missing_commons_cat(rows)
+            hit = wikidata.commons_from_rows(rows)
+            if hit:
+                nearby_result = wikidata.build_dict(hit, lat, lon)
+                if not nearby_result.get("missing"):
+                    return {"elements": elements, "result": nearby_result}
+
+    # Point is in a broad area (e.g. country) — try nearest specific polygon
+    nearby = model.Polygon.nearest(lat, lon)
+    if nearby and nearby.tags:
+        tags: typing.Mapping[str, str] = nearby.tags
+        al = get_admin_level(tags)
+        hit = (
+            hit_from_wikidata_tag(tags)
+            or hit_from_ref_gss_tag(tags)
+            or hit_from_name(tags, lat, lon)
+        )
+        if hit:
+            hit["admin_level"] = al
+            hit["element"] = nearby.osm_id
+            hit["geojson"] = typing.cast(str, nearby.geojson_str)
+            nearby_result = wikidata.build_dict(hit, lat, lon)
+            if not nearby_result.get("missing"):
+                return {"elements": elements, "result": nearby_result}
+
     row = wikidata.geosearch(lat, lon)
     if row:
         hit = wikidata.commons_from_rows([row])