feat: add textarea component (#17465)

This adds the shadcn textarea component along with storybook stories

Figma:
https://www.figma.com/design/WfqIgsTFXN2BscBSSyXWF8/Coder-kit?node-id=1949-13239&t=NSt5S88hAsE4Q9di-1

<img width="612" alt="Screenshot 2025-04-18 at 12 16 57"
src="https://github.com/user-attachments/assets/dcd0281f-5d80-4047-9ba4-e456290ceb61"
/>

site/src/components/Textarea/Textarea.stories.tsx

@@ -0,0 +1,99 @@
+import type { Meta, StoryObj } from "@storybook/react";
+import { expect, userEvent, within } from "@storybook/test";
+import { useState } from "react";
+import { Textarea } from "./Textarea";
+
+const meta: Meta<typeof Textarea> = {
+	title: "components/Textarea",
+	component: Textarea,
+	args: {},
+	argTypes: {
+		value: {
+			control: "text",
+			description: "The controlled value of the textarea",
+		},
+		defaultValue: {
+			control: "text",
+			description: "The default value when initially rendered",
+		},
+		disabled: {
+			control: "boolean",
+			description:
+				"When true, prevents the user from interacting with the textarea",
+		},
+		placeholder: {
+			control: "text",
+			description: "Placeholder text displayed when the textarea is empty",
+		},
+		rows: {
+			control: "number",
+			description: "The number of rows to display",
+		},
+	},
+};
+
+export default meta;
+type Story = StoryObj<typeof Textarea>;
+
+export const WithPlaceholder: Story = {
+	args: {
+		placeholder: "Enter your message here...",
+	},
+};
+
+export const Disabled: Story = {
+	args: {
+		disabled: true,
+		placeholder: "Placeholder",
+	},
+};
+
+export const WithDefaultValue: Story = {
+	args: {
+		defaultValue: "This is some default text in the textarea.",
+	},
+};
+
+export const Large: Story = {
+	args: {
+		rows: 8,
+		placeholder: "Placeholder: A larger textarea with more rows",
+	},
+};
+
+const ControlledTextarea = () => {
+	const [value, setValue] = useState("This is a controlled textarea.");
+	return (
+		<div className="space-y-2">
+			<Textarea
+				value={value}
+				placeholder="Type something..."
+				onChange={(e) => setValue(e.target.value)}
+			/>
+			<div className="text-sm text-content-secondary">
+				Character count: {value.length}
+			</div>
+		</div>
+	);
+};
+
+export const Controlled: Story = {
+	render: () => <ControlledTextarea />,
+};
+
+export const TypeText: Story = {
+	args: {
+		placeholder: "Type something here...",
+	},
+	play: async ({ canvasElement }) => {
+		const canvas = within(canvasElement);
+		const textarea = canvas.getByRole("textbox");
+		await userEvent.type(
+			textarea,
+			"Hello, this is some example text being typed into the textarea!",
+		);
+		expect(textarea).toHaveValue(
+			"Hello, this is some example text being typed into the textarea!",
+		);
+	},
+};

site/src/components/Textarea/Textarea.tsx

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+/**
+ * Copied from shadc/ui on 04/18/2025
+ * @see {@link https://ui.shadcn.com/docs/components/textarea}
+ */
+import * as React from "react";
+
+import { cn } from "utils/cn";
+
+export const Textarea = React.forwardRef<
+	HTMLTextAreaElement,
+	React.ComponentProps<"textarea">
+>(({ className, ...props }, ref) => {
+	return (
+		<textarea
+			className={cn(
+				`flex min-h-[60px] w-full px-3 py-2 text-sm shadow-sm text-content-primary
+				rounded-md border border-border bg-transparent placeholder:text-content-secondary
+				focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-content-link
+				disabled:cursor-not-allowed disabled:opacity-50 disabled:text-content-disabled md:text-sm`,
+				className,
+			)}
+			ref={ref}
+			{...props}
+		/>
+	);
+});