add default prompt to web search

lang/en-US.json

@@ -35,6 +35,7 @@
   "delete": "Delete",
   "signOut": "Sign out",
   "webSearch": "Web Search",
+  "webSearchDefaultPrompt": "Web search results:\n\n{web_results}\nCurrent date: {current_date}\n\nInstructions: Using the provided web search results, write a comprehensive reply to the given query. Make sure to cite results using [[number](URL)] notation after the reference. If the provided search results refer to multiple subjects with the same name, write separate answers for each subject.\nQuery: {query}",
   "welcomeScreen": {
     "introduction1": "is an unofficial client for ChatGPT, but uses the official OpenAI API.",
     "introduction2": "You will need an OpenAI API Key before you can use this client.",