Add HUD class and integrate inventory background; update scene to draw HUD

game/hud.rb

@@ -0,0 +1,9 @@
+class HUD
+  def initialize
+    @inventory_bg = Gosu::Image.new("assets/images/inventory.png", retro: true)
+  end
+
+  def draw
+    @inventory_bg.draw(0, 0, Float::INFINITY)
+  end
+end