Normalize area geometries to two dimensions

backend/app/utils/geometry.py

@@ -3,13 +3,14 @@ from __future__ import annotations
 from typing import Any
 
 from pyproj import Transformer
+from shapely import force_2d
 from shapely.geometry import GeometryCollection, MultiPolygon, Polygon, box, shape
 from shapely.ops import transform
 from shapely.validation import make_valid
 
 
 def normalize_to_multipolygon(raw_geometry: dict[str, Any]) -> MultiPolygon:
-    geom = shape(raw_geometry)
+    geom = force_2d(shape(raw_geometry))
     if geom.is_empty:
         raise ValueError("Geometry is empty")