feat: support var in suggested questions (#17340)

Co-authored-by: crazywoola <427733928@qq.com>

web/i18n/en-US/app-debug.ts

@@ -446,6 +446,7 @@ const translation = {
     writeOpener: 'Edit opener',
     placeholder: 'Write your opener message here, you can use variables, try type {{variable}}.',
     openingQuestion: 'Opening Questions',
+    openingQuestionPlaceholder: 'You can use variables, try typing {{variable}}.',
     noDataPlaceHolder:
       'Starting the conversation with the user can help AI establish a closer connection with them in conversational applications.',
     varTip: 'You can use variables, try type {{variable}}',