game: add magnet pickup

scenes/pickups/pickup_base.tscn

@@ -0,0 +1,24 @@
+[gd_scene load_steps=4 format=3 uid="uid://dr80h4envloce"]
+
+[ext_resource type="Script" uid="uid://bo2oowrbsp2k8" path="res://scenes/pickups/pickup_base.gd" id="1_oto2a"]
+
+[sub_resource type="PlaceholderTexture2D" id="PlaceholderTexture2D_rs1tx"]
+size = Vector2(10, 10)
+
+[sub_resource type="CircleShape2D" id="CircleShape2D_oto2a"]
+radius = 3.16228
+
+[node name="PickupBase" type="Node2D" groups=["pickup"]]
+script = ExtResource("1_oto2a")
+
+[node name="Sprite2D" type="Sprite2D" parent="."]
+position = Vector2(-1, 1)
+texture = SubResource("PlaceholderTexture2D_rs1tx")
+
+[node name="Area2D" type="Area2D" parent="."]
+collision_layer = 16
+collision_mask = 0
+monitoring = false
+
+[node name="CollisionShape2D" type="CollisionShape2D" parent="Area2D"]
+shape = SubResource("CircleShape2D_oto2a")