feat(components/ui): add <Textarea> from shadcn-ui

This patch adds the output of running:

```
$ pnpm shadcn-ui add textarea
```

...and then updating the `bg-transparent` with `bg-white
dark:bg-gray-950` to align with the background colors on the other form
fields (e.g. `<Input>` and `<Button>`).

app/components/ui/textarea.tsx

@@ -0,0 +1,23 @@
+import * as React from 'react'
+
+import { cn } from 'utils/cn'
+
+export type TextareaProps = React.TextareaHTMLAttributes<HTMLTextAreaElement>
+
+const Textarea = React.forwardRef<HTMLTextAreaElement, TextareaProps>(
+  ({ className, ...props }, ref) => {
+    return (
+      <textarea
+        className={cn(
+          'flex min-h-[60px] w-full rounded-md border border-gray-200 border-gray-200 bg-white dark:bg-gray-950 px-3 py-2 text-sm shadow-sm placeholder:text-gray-500 focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-gray-400 disabled:cursor-not-allowed disabled:opacity-50 dark:border-gray-800 dark:border-gray-800 dark:placeholder:text-gray-400 dark:focus-visible:ring-gray-800',
+          className,
+        )}
+        ref={ref}
+        {...props}
+      />
+    )
+  },
+)
+Textarea.displayName = 'Textarea'
+
+export { Textarea }