fix(storybook): remove cubes storybook

It wasn't adding much value and requires a mock Clan context which is a lot of effort at the min.

pkgs/clan-app/ui/src/scene/cubes.stories.tsx

@@ -1,15 +0,0 @@
-import { Meta, StoryObj } from "@kachurun/storybook-solid";
-import { CubeScene } from "./cubes";
-
-const meta: Meta = {
-  title: "scene/cubes",
-  component: CubeScene,
-};
-
-export default meta;
-
-type Story = StoryObj;
-
-export const Default: Story = {
-  args: {},
-};