chore(site): add stories to 404 page (#12470)

Related to https://github.com/coder/coder/issues/12263

site/src/pages/404Page/404Page.stories.tsx

@@ -0,0 +1,13 @@
+import type { Meta, StoryObj } from "@storybook/react";
+import NotFoundPage from "./404Page";
+
+const meta: Meta<typeof NotFoundPage> = {
+  title: "components/NotFoundPage",
+  component: NotFoundPage,
+};
+
+export default meta;
+type Story = StoryObj<typeof NotFoundPage>;
+
+const Example: Story = {};
+export { Example as NotFoundPage };