game: add slime enemy

scenes/enemies/enemy_slime_small.gd

@@ -0,0 +1,19 @@
+class_name EnemySlimeSmall
+extends EnemyBase
+
+@export var color: Color = Color.CHARTREUSE
+@onready var disabled_sprite: Sprite2D = $Sprite2D
+@onready var base_sprite: Sprite2D = $Sprite/BaseSprite
+
+var shader = preload("res://assets/shaders/base_color_tint.gdshader")
+var shader_material: ShaderMaterial
+
+func _ready() -> void:
+	shader_material = ShaderMaterial.new()
+	disabled_sprite.visible = false
+	set_color(color)
+	shader_material.shader = shader
+	base_sprite.material = shader_material
+
+func set_color(new_color: Color) -> void:
+	shader_material.set_shader_parameter("base_color", new_color)