feat(materials): masonry coursing, glass/banner materials, per-slot assignment, telephoto elevations

0.1.4 materials pass plus the camera fix levelling exposed.

Materials (Tools/ue_build_demo_map.py):
- ensure_material() gains optional masonry coursing (world-space course height,
  joint band, joint tint) and roughness variation, so facades read as coursed
  stone/stucco instead of one flat specular plane.
- WorldPosition is in centimetres: course heights in metres are scaled by 100
  (the first attempt divided by 0.55 and the coursing was invisible).
- connect_material_expressions returns False rather than raising, so every link
  now goes through a link() helper that logs failures; UE has no
  MaterialExpressionLess, so the joint mask is Frac -> Divide -> OneMinus -> Clamp.
- New materials: M_FacadeStoneShadow, M_FacadeGlass (specular 0.62 ~ IOR 1.5),
  M_FacadeBanner.
- Material assignment is now per SLOT keyed on the imported slot material name.
  It was slot-0 only, which on the hero is the banner, so stone, shadow stone and
  glazing still wore flat Blender materials. Hero now 4/4 slots.

Cameras (GigLineShotActor + ue_build_review_map):
- Optional per-shot ShotFieldOfView; the shot tuples take a 4th element.
- Elevations use a 42-55 deg lens from across the street: with the cameras
  levelled (0.1.2 follow-up) the building was small in frame, and tilting to fill
  it is what breaks the verticals. hero-facade-front sky 39% -> 20%,
  demo-spawn-view 23% -> 16%.

Screenshots re-rendered for the whole set.

Tools/ue_build_review_map.py

@@ -240,9 +240,9 @@ try:
         # verticals stay parallel. The old shot looked up ~4 deg from 4.2 m at a
         # 7.6 m target, which converged the columns — the one thing an
         # architectural elevation must not do (archviz: "straight verticals").
-        ("hero-facade-front", unreal.Vector(hero_x + 200, -3200, 760), unreal.Vector(hero_x, hero_y + 400, 760)),
+        ("hero-facade-front", unreal.Vector(hero_x + 200, -3200, 760), unreal.Vector(hero_x, hero_y + 400, 760), 42.0),
         # oblique from the north-west, reading the colonnade in depth
-        ("hero-facade-oblique", unreal.Vector(hero_x - 2200, -3400, 620), unreal.Vector(hero_x + 300, hero_y, 700)),
+        ("hero-facade-oblique", unreal.Vector(hero_x - 2200, -3400, 620), unreal.Vector(hero_x + 300, hero_y, 700), 55.0),
     ]
     # --- review shot cameras + save -------------------------------------------
     # Order matters: the review scene is staged in the default (unsaved) world.
@@ -256,6 +256,12 @@ try:
             "shot_rotations",
             [unreal.MathLibrary.find_look_at_rotation(c[1], c[2]) for c in cams])
         shots.set_editor_property("shot_names", [c[0] for c in cams])
+        # Optional 4th element: field of view in degrees. 0 keeps the default 90.
+        # Elevations shot from across the street use a long lens so the building
+        # fills the frame without pitching the camera (archviz: straight
+        # verticals, telephoto for elevations).
+        shots.set_editor_property(
+            "shot_field_of_view", [float(c[3]) if len(c) > 3 else 0.0 for c in cams])
         shots.set_editor_property("quit_when_done", True)
         log(f"staged: ShotSequencer with {len(cams)} cameras: {', '.join(c[0] for c in cams)}")
 
@@ -282,7 +288,7 @@ try:
             # the colonnade's underside.
             # Level horizon for the same reason: a block elevation is read by its
             # verticals, and a pitched camera makes them lean.
-            ("demo-spawn-view", unreal.Vector(-13336, -3100, 620), unreal.Vector(-13336, 1300, 620)),
+            ("demo-spawn-view", unreal.Vector(-13336, -3100, 620), unreal.Vector(-13336, 1300, 620), 48.0),
             # Street level, from the north sidewalk: the old camera sat at Y -400,
             # inside the facade body (which spans Y -1457..-200), so it looked at
             # the unlit back face. Y -2600 is on the sidewalk in front of the lit
@@ -309,6 +315,9 @@ try:
             seq.set_editor_property("shot_rotations",
                                     [unreal.MathLibrary.find_look_at_rotation(c[1], c[2]) for c in demo_shots])
             seq.set_editor_property("shot_names", [c[0] for c in demo_shots])
+            seq.set_editor_property(
+                "shot_field_of_view",
+                [float(c[3]) if len(c) > 3 else 0.0 for c in demo_shots])
             # quit after the demo shots so a dedicated DemoMap capture run
             # terminates cleanly (render_screenshots.sh runs both maps).
             seq.set_editor_property("quit_when_done", True)