asset: two north-side background buildings across Hollywood Blvd

- TCL Chinese Theatre (6925) and Madame Tussaud's (6933) exported from the
  verified OSM blockout with ue_metric_v1 (export_north_buildings.py), with a
  Y-mirror so they land north of the road, across from the hero facade.
- ue_import_north_buildings.py imports + stages them in the DemoMap as
  North_TCL_Chinese / North_Madame_Tussauds (TCL Y 1802..9431, Tussaud's
  1888..7586; hero at Y -1450, road centreline ~0).
- render_screenshots.sh now also runs the DemoMap capture pass; added a
  demo-north-buildings camera, so the new buildings get a review shot.
- README/roadmap updated; flat facade materials pending the 0.1.4 patch.

Tools/export_north_buildings.py

@@ -0,0 +1,91 @@
+# Export the two in-scope north-side background buildings from the OSM blockout.
+#
+#   blender -b --factory-startup Art/blender/blockout/blockout-2026-11-06.blend \
+#       --python Tools/export_north_buildings.py -- --out /tmp/gigline/north
+#
+# The blockout is already in the shared project frame (metres, X east / Y north /
+# Z up, origin Hollywood x Highland), so exporting each object at its own world
+# position preserves the offset from the hero facade. The site export preset
+# (`ue_metric_v1`) is reused verbatim so the metre->centimetre mapping matches.
+
+import argparse
+import os
+import sys
+
+import bpy
+
+BUILDINGS = ("TCL Chinese Theatre", "Madame Tussaud's")
+
+
+def main():
+    argv = sys.argv[sys.argv.index("--") + 1:] if "--" in sys.argv else []
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--out", default="/tmp/gigline/north")
+    args = ap.parse_args(argv)
+    os.makedirs(args.out, exist_ok=True)
+
+    print(f"[north] scene objects: {len(bpy.data.objects)}")
+    for name in BUILDINGS:
+        obj = bpy.data.objects.get(name)
+        if obj is None or obj.type != "MESH":
+            print(f"[north] MISSING {name}")
+            continue
+        bpy.ops.object.select_all(action="DESELECT")
+        obj.select_set(True)
+        bpy.context.view_layer.objects.active = obj
+        mesh = obj.data
+        if not mesh.materials:
+            mat = bpy.data.materials.new(f"M_{name.replace(' ', '_')}")
+            mat.diffuse_color = (0.75, 0.72, 0.68, 1.0)
+            mat.use_nodes = False
+            mesh.materials.append(mat)
+
+        # The blockout sits with the hero (6840, south side) at negative Y. The two
+        # in-scope north buildings must land ACROSS Hollywood Blvd at positive Y in
+        # Unreal. Mirror the exported geometry across the road centreline (Y=0) and
+        # reverse winding; the FBX exporter does not do this for us.
+        new_mesh = mesh.copy()
+        new_obj = obj.copy()
+        new_obj.data = new_mesh
+        new_obj.matrix_world = obj.matrix_world.copy()
+        bpy.context.collection.objects.link(new_obj)
+        import mathutils as mu
+        world = new_obj.matrix_world
+        inv = world.inverted()
+        for v in new_mesh.vertices:
+            wp = world @ v.co
+            wp.y = -wp.y
+            v.co = inv @ wp
+        for poly in new_mesh.polygons:
+            verts = list(poly.vertices)
+            verts.reverse()
+            poly.vertices = verts
+        new_mesh.update()
+        bpy.ops.object.select_all(action="DESELECT")
+        new_obj.select_set(True)
+        bpy.context.view_layer.objects.active = new_obj
+
+        path = os.path.join(args.out, name.replace(" ", "_").replace("'", "") + ".fbx")
+        bpy.ops.export_scene.fbx(
+            filepath=path,
+            use_selection=True,
+            object_types={"MESH"},
+            apply_unit_scale=True,
+            apply_scale_options="FBX_SCALE_NONE",
+            axis_forward="-Y",
+            axis_up="Z",
+            use_space_transform=True,
+            use_mesh_modifiers=True,
+            mesh_smooth_type="OFF",
+            path_mode="AUTO",
+            bake_space_transform=False,
+        )
+        zs = [(world @ v.co).z for v in new_mesh.vertices]
+        print(f"[north] {name:22} verts {len(new_mesh.vertices):5}  z {min(zs):+.2f}..{max(zs):+.2f} m "
+              f"-> {path}")
+        bpy.data.objects.remove(new_obj, do_unlink=True)
+
+    print(f"[north] done")
+
+
+main()