feat: add semantic GIS selection metrics

docs/CODEX_EXECUTION_LOG.md

@@ -8333,3 +8333,35 @@ Next:
 - Generalize the audited historical-land-use operator to the approved regional
   scope, partition source retrieval by municipality and provision the three
   official editions without merging their methodology into current GRB.
+
+## Sprint 201 - Semantic area-selection metrics (2026-07-15)
+
+Implemented:
+- Extended the canonical persisted-vector selection summary with an additive
+  metric set while preserving the existing primary metric fields and envelope.
+- Mapped known data themes to useful units: building footprint, forest, water
+  and parcel surfaces in hectares; roads and linear watercourses in kilometres;
+  population in inhabitants; and intersecting feature counts as supporting
+  evidence.
+- Kept all spatial calculations in PostGIS after transformation to EPSG:31370.
+  No browser-side area/length calculation or synthetic source value was added.
+- Added honest domain limits for building floor area, road capacity and water
+  volume. The current 2D GRB water source cannot support volume without an
+  independently governed depth/bathymetry dataset.
+- Updated the regional GRB operator metadata for future imports and added a
+  compact supporting-metric surface to the map-first result panel.
+
+Validation evidence:
+- Focused temporal and semantic-selection regression set passed 16 tests.
+- Full readiness passed 605 backend tests, backend compilation, the API
+  contract audit, one Alembic head, frontend TypeScript typecheck/build and all
+  shell syntax gates.
+
+Known limitation:
+- Water volume remains unavailable by design. Adding it requires a compatible
+  depth or bathymetry source, coverage validation, units, observation date and
+  a documented integration method.
+
+Next:
+- Validate the semantic metrics against live Mol PostGIS data and then continue
+  the audited regional historical buildings/water/roads import.