feat: advanced prompt (#1330)

Co-authored-by: Joel <iamjoel007@gmail.com>
Co-authored-by: JzoNg <jzongcode@gmail.com>
Co-authored-by: Gillian97 <jinling.sunshine@gmail.com>

web/app/components/base/prompt-editor/plugins/placeholder.tsx

@@ -0,0 +1,13 @@
+import { useTranslation } from 'react-i18next'
+
+const Placeholder = () => {
+  const { t } = useTranslation()
+
+  return (
+    <div className='absolute top-0 left-0 h-full w-full text-sm text-gray-300 select-none pointer-events-none leading-6'>
+      {t('common.promptEditor.placeholder')}
+    </div>
+  )
+}
+
+export default Placeholder