Add governed VMM flood hazard scenarios

docs/API_CONTRACTS.md

@@ -277,6 +277,51 @@ Safety contract:
 - product periods such as `1979_1990` remain explicitly multi-year and are not
   presented as exact annual observations.
 
+### GET `/api/v1/projects/{project_id}/datasets/flood-hazard/products`
+
+Returns the fixed twelve-product VMM flood-depth registry in the canonical
+envelope. Products combine `pluviaal`/`fluviaal`, current climate/climate
+projection 2050 and T10/T100/T1000. Each product keeps the official WCS
+coverage id, probability class, source unit centimetres, normalized unit
+metres, publication metadata, attribution and limitation.
+
+### POST `/api/v1/projects/{project_id}/datasets/flood-hazard/acquire`
+
+Acquires one bounded official VMM OGRK WCS 1.1 coverage behind the synchronous
+Job abstraction. Arbitrary coverage identifiers and service URLs are rejected.
+
+```json
+{
+  "bbox": {"min_x": 5.0, "min_y": 51.1, "max_x": 5.2, "max_y": 51.3, "crs": "EPSG:4326"},
+  "area_id": "optional-project-area-uuid",
+  "product_key": "pluviaal_current_t100",
+  "resolution_m": 5.0,
+  "force_refresh": false
+}
+```
+
+The service tiles municipality-size requests, validates EPSG:31370 and one
+Float32 depth band, converts positive source centimetres to metres, clips to
+the exact persisted Area and stores an ordinary raster Dataset and
+DatasetVersion. Zero/null source cells become transparent nodata. The scenario
+is not a temporal observation and receives no fabricated `observed_at` value.
+
+### POST `/api/v1/projects/{project_id}/datasets/{dataset_id}/raster/flood-hazard/select`
+
+Returns mapped positive-depth area in hectares, share of the selection, mean,
+P90 and maximum modeled local depth and `modelled_max_depth_area_integral_m3`.
+Every result identifies mechanism, climate context, probability class and
+return period. The integral sums local modeled maximum depth times cell area;
+it is explicitly not concurrent flood storage, permanent waterbody content,
+current water level or bathymetry. These unsupported metrics remain listed in
+the response.
+
+### GET `/api/v1/projects/{project_id}/datasets/{dataset_id}/raster/flood-hazard/image`
+
+Returns a constrained transparent PNG for a persisted governed VMM flood-depth
+Dataset. It never accepts an arbitrary path or coverage id and is used by the
+existing MapLibre image-overlay path.
+
 ### GET `/api/v1/projects/{project_id}/datasets`
 
 List datasets.