feat(camera): third-person rig, V toggle, visible body

One pawn, both rigs (ADR-9): a skeletal body hidden in first person, a
collision-tested spring arm, and a toggle that swaps the active camera and the
body's visibility. Shipped default stays first person; -thirdperson starts the
pawn in the third-person rig so the review shot is reproducible, and the
screenshot run passes it.

Three defects found and two fixed:
- The skin material had no SkeletalMesh usage flag, so Unreal silently substituted
  the default grey. That is why the body rendered as clay.
- render_screenshots.sh still called ./Engine/... on this branch (the fix lives on
  the facade branch and never reached main); applied here so the shots generate.
- OPEN: the idle clip is bound and PlayAnimation is called - the run logs the clip
  name - but the body still renders in bind pose, arms out. Recorded with that
  evidence in TODO.md rather than called done.

Shot 5 (demo-third-person) added and documented; camera collision is implemented
but unproven, since the spawn has open space behind it.

Game/GigLine/Source/GigLine/GigLineCharacter.cpp

@@ -1,6 +1,9 @@
 #include "GigLineCharacter.h"
 
+#include "Animation/AnimSequence.h"
 #include "Camera/CameraComponent.h"
+#include "Components/SkeletalMeshComponent.h"
+#include "GameFramework/SpringArmComponent.h"
 #include "Components/CapsuleComponent.h"
 #include "EnhancedInputComponent.h"
 #include "EnhancedInputSubsystems.h"
@@ -28,7 +31,7 @@ static TAutoConsoleVariable<int32> CVarGigLineSetupLogs(
 
 AGigLineCharacter::AGigLineCharacter()
 {
-	PrimaryActorTick.bCanEverTick = false;
+	PrimaryActorTick.bCanEverTick = true;
 
 	// 1.75 m tall, 0.42 m wide, human scale in Unreal units (1 m = 100 uu).
 	GetCapsuleComponent()->InitCapsuleSize(42.0f, 87.5f);
@@ -51,9 +54,59 @@ AGigLineCharacter::AGigLineCharacter()
 	FirstPersonCamera->SetRelativeLocation(FVector(0.0f, 0.0f, 72.5f)); // eye height 1.60 m
 	FirstPersonCamera->bUsePawnControlRotation = true;
 
-	// An eye-level mesh is not needed for 0.1.0; the body is a capsule with a camera.
-	GetMesh()->SetHiddenInGame(true);
+	// Visible body (0.2.0). The animated import carries its own skeleton, so the
+	// clips resolve without a retarget step; it is hidden while the first-person
+	// camera is active and shown in third person.
+	static ConstructorHelpers::FObjectFinder<USkeletalMesh> BodyFinder(
+		TEXT("/Game/Test/Character/Character_Anim.Character_Anim"));
+	if (BodyFinder.Succeeded())
+	{
+		GetMesh()->SetSkeletalMesh(BodyFinder.Object);
+	}
+	// The animated import carries no material of its own; without this the body is
+	// grey clay. The warm skin material was created by the character import.
+	static ConstructorHelpers::FObjectFinder<UMaterialInterface> SkinFinder(
+		TEXT("/Game/Test/Character/M_Character_Export.M_Character_Export"));
+	if (SkinFinder.Succeeded())
+	{
+		GetMesh()->SetMaterial(0, SkinFinder.Object);
+	}
+	static ConstructorHelpers::FObjectFinder<UAnimSequence> IdleFinder(
+		TEXT("/Game/Test/Character/Character_AnimHuman_rig_GigLine_Idle.Character_AnimHuman_rig_GigLine_Idle"));
+	if (IdleFinder.Succeeded())
+	{
+		IdleAnimation = IdleFinder.Object;
+	}
+	static ConstructorHelpers::FObjectFinder<UAnimSequence> WalkFinder(
+		TEXT("/Game/Test/Character/Character_AnimHuman_rig_GigLine_Walk.Character_AnimHuman_rig_GigLine_Walk"));
+	if (WalkFinder.Succeeded())
+	{
+		WalkAnimation = WalkFinder.Object;
+	}
+	GetMesh()->SetRelativeLocation(FVector(0.0f, 0.0f, -87.5f));
+	GetMesh()->SetRelativeRotation(FRotator(0.0f, -90.0f, 0.0f));
 	GetMesh()->SetCollisionEnabled(ECollisionEnabled::NoCollision);
+	GetMesh()->SetHiddenInGame(true);
+
+	// Third-person boom. bDoCollisionTest is the camera-collision feature: the arm
+	// shortens when something is between the pivot and the desired camera position.
+	ThirdPersonArm = CreateDefaultSubobject<USpringArmComponent>(TEXT("ThirdPersonArm"));
+	ThirdPersonArm->SetupAttachment(GetCapsuleComponent());
+	ThirdPersonArm->SetRelativeLocation(FVector(0.0f, 0.0f, 60.0f));
+	ThirdPersonArm->TargetArmLength = ThirdPersonBoomLength;
+	ThirdPersonArm->bUsePawnControlRotation = true;
+	ThirdPersonArm->bDoCollisionTest = true;
+	ThirdPersonArm->ProbeSize = 12.0f;
+	ThirdPersonArm->ProbeChannel = ECollisionChannel::ECC_Camera;
+	ThirdPersonArm->bEnableCameraLag = true;
+	ThirdPersonArm->CameraLagSpeed = 8.0f;
+	ThirdPersonArm->SetAutoActivate(false);
+
+	ThirdPersonCamera = CreateDefaultSubobject<UCameraComponent>(TEXT("ThirdPersonCamera"));
+	ThirdPersonCamera->SetupAttachment(ThirdPersonArm, USpringArmComponent::SocketName);
+	ThirdPersonCamera->bUsePawnControlRotation = false;
+	ThirdPersonCamera->SetAutoActivate(false);
+	ThirdPersonCamera->SetFieldOfView(90.0f);
 
 	// Hard-reference the Enhanced Input assets with ConstructorHelpers so the
 	// cooker always includes them and they load during CDO construction. Runtime
@@ -78,6 +131,8 @@ AGigLineCharacter::AGigLineCharacter()
 		TEXT("/Game/Input/IA_Jump.IA_Jump"));
 	static ConstructorHelpers::FObjectFinder<UInputAction> ResetF(
 		TEXT("/Game/Input/IA_Reset.IA_Reset"));
+	static ConstructorHelpers::FObjectFinder<UInputAction> CamF(
+		TEXT("/Game/Input/IA_ToggleCamera.IA_ToggleCamera"));
 	static ConstructorHelpers::FObjectFinder<UInputAction> PauseF(
 		TEXT("/Game/Input/IA_Pause.IA_Pause"));
 
@@ -89,6 +144,7 @@ AGigLineCharacter::AGigLineCharacter()
 	LookAction = LookF.Object;
 	JumpAction = JumpF.Object;
 	ResetAction = ResetF.Object;
+	ToggleCameraAction = CamF.Object;
 	PauseAction = PauseF.Object;
 
 	if (!MappingContext || !MoveAction || !MoveBackAction || !StrafeAction || !StrafeLeftAction
@@ -138,6 +194,23 @@ void AGigLineCharacter::BeginPlay()
 	StartLocation = GetActorLocation();
 	StartRotation = GetActorRotation();
 
+	// `-thirdperson` starts the pawn in the third-person rig. The first-person view
+	// stays the default (owner decision for 0.1.0), but the screenshot run needs the
+	// body visible without a human pressing V, so the review is reproducible.
+	if (CVarGigLineSetupLogs.GetValueOnGameThread())
+	{
+		UE_LOG(LogTemp, Log,
+			TEXT("GigLine: BeginPlay thirdperson=%d body=%s idle=%s walk=%s"),
+			FParse::Param(FCommandLine::Get(), TEXT("thirdperson")) ? 1 : 0,
+			GetMesh()->GetSkeletalMeshAsset() ? TEXT("ok") : TEXT("nil"),
+			IdleAnimation ? TEXT("ok") : TEXT("nil"),
+			WalkAnimation ? TEXT("ok") : TEXT("nil"));
+	}
+	if (FParse::Param(FCommandLine::Get(), TEXT("thirdperson")))
+	{
+		ToggleCamera();
+	}
+
 	// The PlayerStart sits above grade so the capsule cannot spawn embedded, so
 	// the BeginPlay position is mid-air. Re-capture once the pawn has landed,
 	// otherwise Reset drops the player 1.4 m back into the air every press.
@@ -557,6 +630,10 @@ void AGigLineCharacter::SetupPlayerInputComponent(UInputComponent* PlayerInputCo
 	{
 		Input->BindAction(PauseAction, ETriggerEvent::Started, this, &AGigLineCharacter::TogglePause);
 	}
+	if (ToggleCameraAction)
+	{
+		Input->BindAction(ToggleCameraAction, ETriggerEvent::Started, this, &AGigLineCharacter::ToggleCamera);
+	}
 	if (JumpAction)
 	{
 		Input->BindAction(JumpAction, ETriggerEvent::Started, this, &AGigLineCharacter::StartJump);
@@ -644,6 +721,68 @@ void AGigLineCharacter::Look(const FInputActionValue& Value)
 	AddControllerPitchInput(Axis.Y * LookSensitivity * (bInvertLookY ? -1.0f : 1.0f));
 }
 
+void AGigLineCharacter::Tick(float DeltaSeconds)
+{
+	Super::Tick(DeltaSeconds);
+	// Speed-driven animation state: correct whether the player walked, was pushed,
+	// or fell, and independent of which input produced the movement.
+	UpdateBodyAnimation();
+}
+
+void AGigLineCharacter::ToggleCamera()
+{
+	// Both rigs exist from construction; the toggle only swaps which one is active
+	// and whether the body is drawn. Deactivating the other camera matters: with
+	// two active cameras the view is whichever was registered last.
+	bThirdPerson = !bThirdPerson;
+	FirstPersonCamera->SetActive(!bThirdPerson);
+	ThirdPersonCamera->SetActive(bThirdPerson);
+	GetMesh()->SetHiddenInGame(!bThirdPerson);
+	if (bThirdPerson)
+	{
+		UpdateBodyAnimation();
+	}
+	if (CVarGigLineSetupLogs.GetValueOnGameThread())
+	{
+		UE_LOG(LogTemp, Log, TEXT("GigLine: camera %s"), bThirdPerson ? TEXT("third person") : TEXT("first person"));
+	}
+}
+
+void AGigLineCharacter::UpdateBodyAnimation()
+{
+	if (!bThirdPerson || !GetMesh())
+	{
+		return;
+	}
+	const bool bMoving = GetVelocity().Size2D() > WalkAnimationThreshold;
+	UAnimSequence* Wanted = bMoving ? WalkAnimation.Get() : IdleAnimation.Get();
+	if (!Wanted)
+	{
+		// Logged once: a missing clip presents as an A-posed body, which looks like
+		// an animation problem rather than a missing asset reference.
+		static bool bWarnedMissingClip = false;
+		if (!bWarnedMissingClip)
+		{
+			bWarnedMissingClip = true;
+			UE_LOG(LogTemp, Warning,
+				TEXT("GigLine: body clip missing (idle=%s walk=%s) - body stays in bind pose"),
+				IdleAnimation ? TEXT("ok") : TEXT("nil"),
+				WalkAnimation ? TEXT("ok") : TEXT("nil"));
+		}
+		return;
+	}
+	if (Wanted == PlayingAnimation)
+	{
+		return;
+	}
+	PlayingAnimation = Wanted;
+	if (CVarGigLineSetupLogs.GetValueOnGameThread())
+	{
+		UE_LOG(LogTemp, Log, TEXT("GigLine: playing body clip %s"), *Wanted->GetName());
+	}
+	GetMesh()->PlayAnimation(Wanted, true);
+}
+
 void AGigLineCharacter::ResetToStart()
 {
 	// Reset is a level-restart in miniature: put the body back where it spawned,