build: add initial version number to pubspec.yaml

- Add version 1.0.0 to pubspec.yaml for initial release

Author: fulleni

pubspec.yaml

@@ -2,6 +2,7 @@ name: flutter_news_app_api_server_full_source_code
 description: The complete backend API server for the Flutter News App Toolkit, built with Dart Frog. Powers authentication, data management, user settings, and more.
 repository: https://github.com/flutter-news-app-full-source-code/flutter-news-app-api-server-full-source-code
 publish_to: none
+version: 1.0.0
 
 environment:
   sdk: ^3.9.0