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.

Game/GigLine/Source/GigLine/GigLineShotActor.cpp

@@ -1,6 +1,7 @@
 #include "GigLineShotActor.h"
 
 #include "Camera/CameraActor.h"
+#include "Camera/CameraComponent.h"
 #include "Engine/World.h"
 #include "GameFramework/PlayerController.h"
 #include "UnrealClient.h"
@@ -83,6 +84,15 @@ void AGigLineShotActor::NextShot()
 	Params.ObjectFlags |= RF_Transient;
 	CurrentCamera = GetWorld()->SpawnActor<ACameraActor>(
 		ACameraActor::StaticClass(), ShotLocations[CurrentShot], ShotRotations[CurrentShot], Params);
+	if (ShotFieldOfView.IsValidIndex(CurrentShot) && ShotFieldOfView[CurrentShot] > 0.0f)
+	{
+		if (UCameraComponent* Cam = CurrentCamera->GetCameraComponent())
+		{
+			// Long lens for elevations: fills the frame from across the street
+			// without pitching the camera, so verticals stay parallel.
+			Cam->SetFieldOfView(ShotFieldOfView[CurrentShot]);
+		}
+	}
 	PlayerController->SetViewTarget(CurrentCamera);
 
 	SettleCountdown = SettleSeconds;

Game/GigLine/Source/GigLine/GigLineShotActor.h

@@ -36,6 +36,16 @@ public:
 	UPROPERTY(EditAnywhere, BlueprintReadWrite)
 	TArray<FString> ShotNames;
 
+	/**
+	 * Optional per-shot field of view (degrees), same index as ShotLocations.
+	 * Zero or missing entries keep the engine default (90 deg). Elevation shots
+	 * taken from across the street need a long lens: a level camera 45 m out with
+	 * the default FOV leaves the building small in frame, and tilting it up to fill
+	 * the frame is what breaks the verticals.
+	 */
+	UPROPERTY(EditAnywhere, BlueprintReadWrite)
+	TArray<float> ShotFieldOfView;
+
 	/** Seconds to let the view target settle before the capture. Resolution comes from the runner's -ResX/-ResY. */
 	UPROPERTY(EditAnywhere, BlueprintReadWrite)
 	float SettleSeconds = 0.35f;