Add rib_web to Brain output + import_profile draws rib material

Brain: profile_assembly.py now exports 'rib_web' — the actual material
geometry from Shapely boolean (exterior + interior rings). This is the
rib shape, not the pocket cutouts.

import_profile.py: prefers rib_web when available, drawing exterior +
interior polyline rings directly. Falls back to pocket-based drawing
for older rib JSONs without rib_web.

tools/adaptive-isogrid/src/brain/profile_assembly.py

@@ -106,10 +106,28 @@ def profile_to_json(ribbed_plate, pockets, geometry, params):
                 'is_circular': True,
             })
 
+    # Rib web profile: the actual material geometry from Shapely boolean
+    # This is what NX needs to draw — the ribs, not the pockets.
+    rib_web_rings = []
+    if ribbed_plate.geom_type == 'Polygon':
+        polys = [ribbed_plate]
+    elif ribbed_plate.geom_type == 'MultiPolygon':
+        polys = list(ribbed_plate.geoms)
+    else:
+        polys = []
+
+    for poly in polys:
+        ring = {
+            'exterior': [list(c) for c in poly.exterior.coords],
+            'interiors': [[list(c) for c in interior.coords] for interior in poly.interiors],
+        }
+        rib_web_rings.append(ring)
+
     return {
         'valid': True,
         'outer_boundary': outer,
         'pockets': pocket_data,
         'holes': hole_data,
+        'rib_web': rib_web_rings,
         'parameters_used': params,
     }