Implement production vertical slice foundation

game/application/vehicle/pilot_use_case.gd

@@ -0,0 +1,32 @@
+class_name PilotUseCase
+extends RefCounted
+
+const VehicleCommand = preload("res://game/application/vehicle/vehicle_command.gd")
+const VehicleCommandResult = preload(
+	"res://game/application/vehicle/vehicle_command_result.gd"
+)
+const VehicleMotionPort = preload("res://game/application/interfaces/vehicle_motion_port.gd")
+
+var _motion_port: VehicleMotionPort
+var _last_sequence := -1
+
+
+func _init(motion_port: VehicleMotionPort) -> void:
+	_motion_port = motion_port
+
+
+func execute(command: VehicleCommand) -> VehicleCommandResult:
+	if command == null:
+		return VehicleCommandResult.new(false, -1, "vehicle command is missing")
+	var error: String = command.validation_error()
+	if not error.is_empty():
+		return VehicleCommandResult.new(false, command.sequence, error)
+	if command.sequence != _last_sequence + 1:
+		return VehicleCommandResult.new(
+			false,
+			command.sequence,
+			"vehicle command sequence is not consecutive"
+		)
+	_motion_port.apply_command(command)
+	_last_sequence = command.sequence
+	return VehicleCommandResult.new(true, command.sequence)