feat: add a small smoke asset

sonic-radiance.love/assets/sprites/gfx/smallsmoke.lua

@@ -0,0 +1,18 @@
+return {
+  metadata = {
+    height      = 16,
+    width       = 16,
+    defaultAnim = "default",
+    ox          = 8,
+    oy          = 8,
+  },
+  animations = {
+    ["default"] = {
+      startAt     = 1,
+      endAt       = 8,
+      loop        = 1,
+      speed       = 15,
+      pauseAtEnd  = false,
+    },
+  }
+}