fix(placement): character and car stand on the ground, not above it

Both floats had different causes and both were measured.

Character: the player start sat at Z 600 while the capsule settles at Z 561 on this
pavement - the QA self-test has been reporting that settle height all along - so the soles
hung 39 cm in the air. The start now uses the measured 561.

Car: the template's lowest geometry is exhaust and underbody, so grounding the model on its
whole bounding box left the tyres 4 cm above the origin. It is grounded on its WHEELS now.
The staged height is 342 rather than the traced road height of 366, because at 367 the
render still showed a gap: the trace and the visible road mesh disagree by about 25 cm at
that spot, and the number is recorded as empirical rather than derived.

Also adds a foot-contact log to the character at BeginPlay (actor Z, ground, capsule half,
mesh bottom, gap) so the next float is a measurement rather than a look.

Game/GigLine/Source/GigLine/GigLineCharacter.cpp

@@ -340,6 +340,21 @@ void AGigLineCharacter::BeginPlay()
 		}
 	}
 
+	// Foot-contact diagnostic: how far the body's lowest point sits above the ground.
+	if (UWorld* World = GetWorld())
+	{
+		FHitResult Hit;
+		FCollisionQueryParams Q(TEXT("GigLineFoot"), false, this);
+		const bool bGround = World->LineTraceSingleByChannel(Hit, GetActorLocation(),
+			GetActorLocation() - FVector(0.f, 0.f, 3000.f), ECC_Visibility, Q);
+		const float CapsuleHalf = GetCapsuleComponent() ? GetCapsuleComponent()->GetScaledCapsuleHalfHeight() : -1.f;
+		const float MeshBottom = GetMesh() ? (GetMesh()->Bounds.Origin - GetMesh()->Bounds.BoxExtent).Z : 0.f;
+		UE_LOG(LogTemp, Warning,
+			TEXT("GigLine foot: actor Z %.0f, ground %.0f, capsule half %.0f, mesh bottom %.0f, gap %.0f cm"),
+			GetActorLocation().Z, bGround ? Hit.ImpactPoint.Z : -9999.f, CapsuleHalf, MeshBottom,
+			bGround ? MeshBottom - Hit.ImpactPoint.Z : -9999.f);
+	}
+
 	bWalkForever = FParse::Param(FCommandLine::Get(), TEXT("walk"));
 	bCameraTest = FParse::Param(FCommandLine::Get(), TEXT("cameratest"));