fix: make vector ingestion canonical and atomic

backend/app/services/vector_feature_service.py

@@ -8,6 +8,7 @@ from geoalchemy2.shape import from_shape
 from geoalchemy2.shape import to_shape
 from shapely.geometry import mapping
 from shapely.geometry import shape
+from shapely.ops import transform as transform_geometry
 from shapely.validation import make_valid
 from sqlalchemy import Float, cast, func
 
@@ -265,6 +266,8 @@ class VectorFeatureService:
                 geometry = make_valid(geometry)
             if geometry.is_empty or not geometry.is_valid:
                 raise AppError(code="INVALID_GEOMETRY", message=f"Invalid feature geometry at index {index}", status_code=400)
+            if geometry.has_z:
+                geometry = transform_geometry(lambda x, y, z=None: (x, y), geometry)
 
             properties = feature.get("properties") if isinstance(feature.get("properties"), dict) else {}
             source_feature_id = feature.get("id")