Implement health bar system: add HealthBar class for managing health, integrate health updates in HUDLayer, and modify enemy attack handling to reflect damage taken.

game/hud/health.rb

@@ -0,0 +1,27 @@
+class HealthBar
+  attr_reader :health, :max_health
+
+  def initialize(max_health)
+    @max_health = max_health
+    @health = max_health
+  end
+
+  def take_damage(amount)
+    @health -= amount
+    @health = 0 if @health < 0
+  end
+
+  def heal(amount)
+    @health += amount
+    @health = @max_health if @health > @max_health
+  end
+
+  def draw(x, y)
+    # Draw the background of the health bar (red)
+    Gosu.draw_rect(x, y, 100, 10, Gosu::Color::RED)
+
+    # Draw the foreground of the health bar (green) based on current health
+    health_width = (health.to_f / max_health) * 100
+    Gosu.draw_rect(x, y, health_width, 10, Gosu::Color::GREEN)
+  end
+end