Playertest: scene/script system refactor and Wii ABI fix

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

assets/entities/cube.lua

@@ -0,0 +1,25 @@
+local Cube = setmetatable({}, { __index = Entity })
+Cube.__index = Cube
+
+function Cube.new()
+  local self = Entity.new()
+  setmetatable(self, Cube)
+  self:add(Entity.POSITION)
+  self.position.x = 0
+  self.position.y = 0
+  self.position.z = 0
+  self:add(Entity.MESH)
+  self:add(Entity.MATERIAL)
+  self.material.color = colorRed()
+  return self
+end
+
+function Cube:update()
+  local speed = 3.0
+  local dx = inputAxis(INPUT_ACTION_LEFT, INPUT_ACTION_RIGHT)
+  local dz = inputAxis(INPUT_ACTION_UP, INPUT_ACTION_DOWN)
+  self.position.x = self.position.x + dx * speed * TIME.delta
+  self.position.z = self.position.z + dz * speed * TIME.delta
+end
+
+return Cube