Route dossier, geocode, and Wikimedia through the backend (#351, #352, #360)

Proxy region dossier, Sentinel search, Wikipedia, and Wikidata via self-hosted
APIs; remove LocateBar client-side Nominatim fallback; migrate legacy shadow-
operator handles to operator- prefix.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/test_wikimedia_proxy_routes.py

@@ -0,0 +1,34 @@
+"""Backend Wikimedia proxy routes (#360)."""
+from __future__ import annotations
+
+from unittest.mock import patch
+
+import pytest
+
+
+def test_wikipedia_summary_route_returns_payload(client):
+    sample = {
+        "title": "Paris",
+        "description": "capital",
+        "extract": "Paris is the capital of France.",
+        "thumbnail": "https://example.org/t.jpg",
+        "type": "standard",
+    }
+    with patch(
+        "services.region_dossier.fetch_wikipedia_page_summary",
+        return_value=sample,
+    ):
+        r = client.get("/api/wikipedia/summary", params={"title": "Paris"})
+    assert r.status_code == 200
+    assert r.json()["title"] == "Paris"
+
+
+def test_wikidata_sparql_route_returns_bindings(client):
+    bindings = [{"x": {"value": "1"}}]
+    with patch(
+        "services.region_dossier.fetch_wikidata_sparql_bindings",
+        return_value=bindings,
+    ):
+        r = client.post("/api/wikidata/sparql", json={"query": "SELECT ?x WHERE {}"})
+    assert r.status_code == 200
+    assert r.json()["bindings"] == bindings