Add hit component and effects; update player and enemy scenes to integrate hit feedback

scripts/components/hit_component.gd

@@ -4,6 +4,8 @@ extends Node
 @export var sprite: Sprite2D
 @export var health_component: HealthComponent
 @export var hit_duration: float = 0.1
+@export var hit_fx: GPUParticles2D
+@export var flash_mode: bool = true
 
 
 func _ready() -> void:
@@ -15,26 +17,41 @@ func _ready() -> void:
 		printerr("No sprite assigned!")
 		return
 
-	if sprite.material:
+	if sprite.material and flash_mode:
 		sprite.material = sprite.material.duplicate()
 
 
 func activate() -> void:
+	if not flash_mode:
+		return
 	sprite.material.set_shader_parameter("enabled", true)
 
 
 func deactivate() -> void:
+	if not flash_mode:
+		return
 	sprite.material.set_shader_parameter("enabled", false)
 
 
-func on_health_change(delta: float, _total_health: float) -> void:
+func on_health_change(delta: float, total_health: float) -> void:
 	if delta < 0:
 		activate()
 		await get_tree().create_timer(hit_duration).timeout
 		deactivate()
 
+		if total_health > 0:
+			handle_hit_fx()
+
 
 func on_death() -> void:
 	activate()
 	await get_tree().create_timer(hit_duration).timeout
-	deactivate()
+	deactivate()
+
+
+func handle_hit_fx() -> void:
+	if not hit_fx:
+		return
+
+	hit_fx.restart()
+	hit_fx.emitting = true