Preserve native orthophoto detail for training

docs/API_CONTRACTS.md

@@ -385,6 +385,7 @@ least 99% of it.
   "bbox": {"min_x": 5.10, "min_y": 51.17, "max_x": 5.11, "max_y": 51.18, "crs": "EPSG:4326"},
   "area_id": "optional-project-area-uuid",
   "product_key": "most_recent",
+  "resolution_m": 0.25,
   "force_refresh": false
 }
 ```
@@ -394,6 +395,12 @@ identifies the raster Dataset; `result_json` contains provider, layer, pixel
 dimensions, EPSG:4326/EPSG:31370 bounds, sampling resolution, attribution,
 cache reuse and limitation text. Historical products also persist their
 observation/validity period and a spatially scoped temporal-series key.
+`resolution_m` is optional (0.1-2.0 m) and can never be finer than the
+allowlisted product's native resolution. It exists for governed training and
+review exports; ordinary workbench requests retain the configured 1 m default.
+For rolling `latest` products, acquisition time is not represented as the
+per-pixel observation date: provenance explicitly records
+`observation_time_precision=unknown_per_pixel`.
 
 ### GET `/api/v1/projects/{project_id}/datasets/grb/products`