Started boss wave and iniital assets; broke out parallax speed change

functionality.

scenes/parallax_clouds.gd

@@ -0,0 +1,17 @@
+extends Node2D
+
+var scroll_multiplier: float = 200
+
+@onready var parallax_nodes = get_tree().get_nodes_in_group("parallax_clouds")
+
+func _ready():
+  EventBus.cloud_speed.connect(_on_cloud_speed)
+
+func _on_cloud_speed():
+  $CoffeeBuoy.hide()
+  for node in parallax_nodes:
+      if node is Parallax2D:
+        var current_autoscroll = node.get_autoscroll()
+        current_autoscroll.y += scroll_multiplier
+        node.set_autoscroll(current_autoscroll)
+