docs(ui): add stories for Error page

app/error.stories.ts

@@ -0,0 +1,79 @@
+import Error from './error.vue'
+import type { Meta, StoryObj } from '@storybook-vue/nuxt'
+import type { NuxtError } from '#app'
+
+const meta = {
+  title: 'pages/error',
+  component: Error,
+  parameters: {
+    layout: 'fullscreen',
+  },
+} satisfies Meta<typeof Error>
+
+export default meta
+type Story = StoryObj<typeof meta>
+
+/** Package, org, or page not found. */
+export const NotFound: Story = {
+  args: {
+    error: {
+      status: 404,
+    } as NuxtError,
+  },
+}
+
+/** Unauthorized access - shown when authentication is required. */
+export const Unauthorized: Story = {
+  args: {
+    error: {
+      status: 401,
+    } as NuxtError,
+  },
+}
+
+/** Generic server error with default message. */
+export const ServerError: Story = {
+  args: {
+    error: {
+      status: 500,
+    } as NuxtError,
+  },
+}
+
+/** Service unavailable - occurs when external services (jsDelivr, npm registry) fail. */
+export const ServiceUnavailable: Story = {
+  args: {
+    error: {
+      status: 503,
+    } as NuxtError,
+  },
+}
+
+export const Teapot: Story = {
+  args: {
+    error: {
+      status: 418,
+    } as NuxtError,
+  },
+}
+
+/** Error with a message. */
+export const WithMessage: Story = {
+  args: {
+    error: {
+      status: 404,
+      message: 'The page you are looking for does not exist.',
+    } as NuxtError,
+  },
+}
+
+/** Error with a detailed message to test text wrapping and layout. */
+export const LongMessage: Story = {
+  args: {
+    error: {
+      status: 500,
+      message:
+        'Internal server error. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean tristique ex ac nisi dapibus maximus. Curabitur feugiat lorem eros, sed eleifend purus facilisis at.',
+    } as NuxtError,
+  },
+}