fix(vehicle): enable ChaosVehiclesPlugin so the Chaos vehicle is actually created

The Chaos vehicle never existed: ChaosVehiclesPlugin is EnabledByDefault=false and
was absent from GigLine.uproject, so FChaosVehicleManager was null and
OnCreatePhysicsState skipped CreateVehicle() (read from the engine source). The
pawn stayed at setups=4 wheels=0 output=null and the mesh fell back to the regular
rigid-body solver, which is what teleported upward.

- Enable ChaosVehiclesPlugin in GigLine.uproject. CreateVehicle() now runs:
  'wheels 4', 'output present', 'setups=4 wheels=4'.
- Drop the constructor's SetSimulatePhysics(true) / collision-profile override: the
  Chaos movement component drives the mesh through async physics, and forcing the
  regular solver kept the body out of the vehicle solver.

The plugin fix turns the teleport into a stable 'float at Z 545' (540 cm above the
floor) in both probe maps - suspension tuning is the next bug.

Game/GigLine/GigLine.uproject

@@ -14,6 +14,10 @@
 		{
 			"Name": "EnhancedInput",
 			"Enabled": true
+		},
+		{
+			"Name": "ChaosVehiclesPlugin",
+			"Enabled": true
 		}
 	]
 }

Game/GigLine/Source/GigLine/GigLineVehicle.cpp

@@ -65,9 +65,12 @@ AGigLineVehicle::AGigLineVehicle(const FObjectInitializer& ObjectInitializer)
 		{
 			Body->SetSkeletalMesh(MeshFinder.Object);
 		}
-		Body->SetCollisionEnabled(ECollisionEnabled::QueryAndPhysics);
-		Body->SetCollisionProfileName(TEXT("PhysicsActor"));
-		Body->SetSimulatePhysics(true);
+		// The Chaos vehicle movement component drives this mesh through its async physics; it
+		// calls CreateVehicle() on the movement component, which builds the wheels and the
+		// vehicle state. Calling SetSimulatePhysics(true) here instead put the mesh into the
+		// REGULAR rigid-body solver, which is why CreateVehicle() never ran (output null,
+		// wheels 0) and why the plain body then teleported upward in DemoMap. Leave the physics
+		// to the movement component.
 	}
 
 	if (UChaosWheeledVehicleMovementComponent* Movement =