Implement traps system: add Trap, Landmine, and EventHorizon classes with collision detection and interaction logic; integrate trap handling in the game scene and enemy AI.

game/traps/landmine.rb

@@ -0,0 +1,13 @@
+require_relative 'base'
+
+class Landmine < Trap
+  def initialize(x, y)
+    super(x, y)
+    @sprite = Gosu::Image.new("assets/images/landmine.png", retro: true)
+  end
+
+  def stepped_on(_)
+    $bus.emit(:blast, @x, @y, 30, 30, :unsafe) # blast radius of 30 and damage of 30, and mark it as unsafe for the player
+    true # to destroy the trap
+  end
+end