Add bounded GRB map acquisition

backend/README.md

@@ -1360,6 +1360,38 @@ idempotent for the exact plan/raster checksum, creates a new immutable raster
 Dataset and DatasetVersion with the official edition, and retains every older
 snapshot. No command is scheduled or invoked by startup or browser actions.
 
+## Governed bounded GRB acquisition
+
+`GET /api/v1/projects/{project_id}/datasets/grb/products` exposes four fixed
+official vector products: building footprints, road segments, water
+surfaces/lines and administrative parcels. `POST .../datasets/grb/acquire`
+accepts an EPSG:4326 rectangle, optional project Area, one product key and an
+explicit refresh flag.
+
+The service queries only the allowlisted GRB OGC API collection paths, follows
+complete same-host pagination and clips every geometry to `bbox ∩ Area`.
+It explicitly requests OGC CRS84 GeoJSON for bbox and output; the native
+EPSG:31370 storage CRS remains provenance rather than being guessed from raw
+coordinates.
+Requests fail closed above 20 km per side, 200 pages, 150,000 retained
+features, 20 MiB per page or 256 MiB total. No partial Dataset is persisted
+when a limit is exceeded. Official ids, request URLs, page checksums and the
+final artifact checksum are retained as provenance.
+
+Persistence uses the existing synchronous Job plus
+`DatasetService.import_vector_bytes`, so Dataset, DatasetVersion and
+VectorFeature rows remain one canonical flow. The browser never contacts the
+provider directly. Exact request identities are reused for 24 hours. Buildings
+return footprint area in hectares, roads return line length in kilometres,
+water returns surface area plus supporting water-line length, and parcels
+return mapped area. GRB cannot provide water volume, legal parcel boundaries
+or traffic information.
+
+Settings: `GRB_ENABLED`, `GRB_OGC_API_URL`, `GRB_MIN_SIDE_M`,
+`GRB_MAX_SIDE_M`, `GRB_PAGE_SIZE`, `GRB_MAX_PAGES`, `GRB_MAX_FEATURES`,
+`GRB_TIMEOUT_SECONDS`, `GRB_MAX_RESPONSE_MB`,
+`GRB_MAX_TOTAL_RESPONSE_MB` and `GRB_CACHE_TTL_HOURS`.
+
 ## Governed DHMV terrain acquisition
 
 `GET /api/v1/projects/{project_id}/datasets/dhmv/products` exposes the fixed