Add textarea story.

stories/text-area.stories.tsx

@@ -0,0 +1,15 @@
+import type { Meta, StoryObj } from "@storybook/react";
+import { Textarea } from "src/components/ui/textarea";
+
+const meta: Meta<typeof Textarea> = {
+  component: Textarea,
+};
+
+export default meta;
+type Story = StoryObj<typeof Textarea>;
+
+export const Default: Story = {
+  args: {
+    placeholder: "Type your message here.",
+  },
+};