fix(hero): export smoothing groups; give the facade real collision

UE export hygiene (unreal-export skill checklist) plus a gameplay defect the new
probe caught:

- FBX export now uses mesh_smooth_type="FACE" (was OFF, which is why every import
  logged "No smoothing group information was found"), and the round parts are
  shaded with shade_smooth_by_angle(35 deg) before export, so columns and
  medallions read round instead of faceted.
- SM_HeroFacade had complex-only collision, so capsule sweeps and line traces
  passed through the wall: the player could walk through the hero facade.
  auto_generate_collision was tried and rejected (coarse hulls bulged into the
  street; the QA wall probe went 0/35 -> 2/35). It now uses UseComplexAsSimple,
  saved on the asset, like the terrain.
- New -qaselftest facade occlusion probe: 40 m traces sideways from the road
  centre at walking height, required only where a building is staged (explicit X
  spans mirroring ue_build_demo_map). Result 0/9 -> PASS, alongside transect
  0 holes and wall probe 0/35.

Docs: release-checks records the probe and both collision attempts; Tools/README
lists the new phase; MEMORY records the smoothing/collision lessons.

Tools/hero_facade_build.py

@@ -74,7 +74,7 @@ def cube(name, x, y, z, dx, dy, dz, material=None):
     return obj
 
 
-def cylinder(name, x, y, z0, z1, radius, material, vertices=24):
+def cylinder(name, x, y, z0, z1, radius, material, vertices=24, smooth=True):
     bpy.ops.mesh.primitive_cylinder_add(
         vertices=vertices,
         radius=radius,
@@ -85,6 +85,11 @@ def cylinder(name, x, y, z0, z1, radius, material, vertices=24):
     obj.name = name
     if material:
         obj.data.materials.append(material)
+    if smooth:
+        # Round parts must shade smoothly *around* the axis while keeping the
+        # caps creased. Without this the columns read as faceted prisms, and the
+        # FBX carries no smoothing groups at all (Unreal warns about it).
+        bpy.ops.object.shade_smooth_by_angle(angle=math.radians(35.0))
     return obj
 
 
@@ -313,7 +318,9 @@ def export_fbx(path):
         axis_up="Z",
         use_space_transform=True,
         use_mesh_modifiers=True,
-        mesh_smooth_type="OFF",
+        # "FACE" exports smoothing groups; without it every import logs
+        # "No smoothing group information was found for this mesh".
+        mesh_smooth_type="FACE",
         path_mode="AUTO",
         bake_space_transform=False,
     )