Add bounded GRB map acquisition

backend/app/providers/grb.py

@@ -9,12 +9,26 @@ class GRBProvider(BaseReferenceProvider):
             provider_name="grb",
             display_name="GRB",
             authority_level="authoritative",
-            supported_layers=["buildings", "roads", "parcels"],
+            supported_layers=["buildings", "roads", "water", "parcels"],
             supported_geometry_types=["Polygon", "MultiPolygon", "LineString", "MultiLineString"],
-            supported_query_modes=["area"],
-            fetch_signature="POST /api/v1/external/grb/fetch",
-            limitation_message="GRB live WFS/download integration is not configured in Sprint 7B.",
-            attribution="Digitaal Vlaanderen - Basiskaart Vlaanderen (GRB)",
-            license_note="Use must follow Digitaal Vlaanderen open data and attribution terms.",
-            configured=False,
+            supported_query_modes=["bbox", "persisted_area"],
+            fetch_signature="POST /api/v1/projects/{project_id}/datasets/grb/acquire",
+            limitation_message=(
+                "Alleen expliciet begrensde selecties tot 20 km per zijde worden opgehaald. "
+                "Volledige providerdownloads en onbeperkte queries zijn niet toegestaan."
+            ),
+            attribution="Bron: Grootschalig Referentie Bestand Vlaanderen, Digitaal Vlaanderen",
+            license_note="Hergebruik volgens de open-datavoorwaarden en bronvermelding van Digitaal Vlaanderen.",
+            configured=True,
         )
+
+    def fetch(self, project_id: str, area_id: str | None, layers: list[str]) -> dict:
+        del project_id, area_id, layers
+        return {
+            "provider": self.provider_name,
+            "status": "bounded_request_required",
+            "message": (
+                "Use POST /api/v1/projects/{project_id}/datasets/grb/acquire with an EPSG:4326 "
+                "bounding box and one governed product key."
+            ),
+        }