feat(nursery): add Cradle component with pendulum rocking animation

scripts/objects/cradle.gd

@@ -0,0 +1,38 @@
+## Cradle — rocks with a pendulum rotation when tapped.
+class_name Cradle extends Node2D
+
+enum State { IDLE, ROCKING }
+
+const ROCK_ANGLE: float = 15.0
+const ROCK_DURATION: float = 0.5
+const BUTTON_HALF_SIZE: float = 80.0
+
+var _state: State = State.IDLE
+
+
+func _input(event: InputEvent) -> void:
+	if _state != State.IDLE:
+		return
+	var screen_pos: Vector2
+	if event is InputEventScreenTouch and event.pressed:
+		screen_pos = event.position
+	elif event is InputEventMouseButton and event.pressed and event.button_index == MOUSE_BUTTON_LEFT:
+		screen_pos = event.position
+	else:
+		return
+	var canvas_transform: Transform2D = get_viewport().get_canvas_transform()
+	var world_pos: Vector2 = canvas_transform.affine_inverse() * screen_pos
+	var local_pos: Vector2 = to_local(world_pos)
+	if abs(local_pos.x) <= BUTTON_HALF_SIZE and abs(local_pos.y) <= BUTTON_HALF_SIZE:
+		_start_rocking()
+
+
+func _start_rocking() -> void:
+	_state = State.ROCKING
+	var tween: Tween = create_tween()
+	tween.set_ease(Tween.EASE_IN_OUT)
+	tween.set_trans(Tween.TRANS_SINE)
+	tween.tween_property(self, "rotation_degrees", ROCK_ANGLE, ROCK_DURATION)
+	tween.tween_property(self, "rotation_degrees", -ROCK_ANGLE, ROCK_DURATION)
+	tween.tween_property(self, "rotation_degrees", 0.0, ROCK_DURATION * 0.5)
+	tween.finished.connect(func() -> void: _state = State.IDLE)