Fix extrusion: catch ImportError on triangle and fallback to earcut

app.py

@@ -152,15 +152,14 @@ def create_3d_model(buildings: List[Dict]) -> trimesh.Scene:
             continue
         
         # extrude: prefer triangle if available, otherwise earcut
-            try:
-                extruded = trimesh.creation.extrude_polygon(polygon, height, engine="triangle")
-            except (ImportError, ValueError) as e:
-                if debug:
-                    print(f"   ↳ triangle engine unavailable ({e}), falling back to earcut")
-                extruded = trimesh.creation.extrude_polygon(polygon, height, engine="earcut")
-            
+        try:
+            extruded = trimesh.creation.extrude_polygon(polygon, height, engine="triangle")
+        except (ImportError, ValueError) as e:
             if debug:
-                print(f"   ↳ extruded mesh vertices={len(extruded.vertices)}, faces={len(extruded.faces)}")
+                print(f"   ↳ triangle engine unavailable ({e}), falling back to earcut")
+            extruded = trimesh.creation.extrude_polygon(polygon, height, engine="earcut")
+        if debug:
+            print(f"   ↳ extruded mesh vertices={len(extruded.vertices)}, faces={len(extruded.faces)}")
             
             # orientation fix
             transform_x = trimesh.transformations.rotation_matrix(np.pi/2, (1, 0, 0))