wip sell boxes and sell mechanics, move coins to inventory items

data/coin.tres

@@ -0,0 +1,13 @@
+[gd_resource type="Resource" script_class="InventoryItem" load_steps=3 format=3 uid="uid://dbxrlw5ggh67j"]
+
+[ext_resource type="Texture2D" uid="uid://cb6qv3c0iojfl" path="res://icon.svg" id="1_eakc4"]
+[ext_resource type="Script" path="res://src/lib/inventory_item.gd" id="2_lrh23"]
+
+[resource]
+script = ExtResource("2_lrh23")
+icon = ExtResource("1_eakc4")
+name = "Coin"
+id = &"coin"
+stackable = true
+stack_limit = 100
+sells_for = 0

data/coin_flower.tres

@@ -10,3 +10,4 @@ name = "Coin Flower"
 id = &"coin_flower"
 stackable = true
 stack_limit = 9
+sells_for = 2

data/water_bomb.tres

@@ -10,4 +10,6 @@ icon = ExtResource("1_g8c3q")
 model = ExtResource("2_5cxkh")
 name = "Water Bomb"
 id = &"water_bomb"
-count = 0
+stackable = false
+stack_limit = 8
+sells_for = 0