chore: switch app environment from demo to development

- Changed the appEnvironment constant from AppEnvironment.demo to AppEnvironment.development in the main.dart file.
- This modification sets the application to run in development mode, which may affect logging, error reporting, and other debug-specific features.

Author: fulleni

lib/main.dart

@@ -6,7 +6,7 @@ import 'package:flutter_news_app_mobile_client_full_source_code/app/services/spl
 import 'package:flutter_news_app_mobile_client_full_source_code/bootstrap.dart';
 
 // Define the current application environment (production/development/demo).
-const appEnvironment = AppEnvironment.demo;
+const appEnvironment = AppEnvironment.development;
 
 void main() async {
   final appConfig = switch (appEnvironment) {