Add latest version check and update prompt to UI

Introduces backend and frontend logic to fetch the latest NapCat version tag from multiple sources, exposes a new API endpoint, and adds a UI prompt to notify users of new versions with an update button. Also includes minor code style improvements in dialog context.

packages/napcat-webui-frontend/src/controllers/webui_manager.ts

@@ -48,6 +48,12 @@ export default class WebUIManager {
     return data.data;
   }
 
+  public static async getLatestTag () {
+    const { data } =
+      await serverRequest.get<ServerResponse<string>>('/base/getLatestTag');
+    return data.data;
+  }
+
   public static async UpdateNapCat () {
     const { data } = await serverRequest.post<ServerResponse<any>>(
       '/UpdateNapCat/update',