Linux build system correction. New visual treatment

Co-authored-by: Copilot <copilot@github.com>

pubspec.yaml

@@ -63,6 +63,8 @@ flutter:
   # included with your application, so that you can use the icons in
   # the material Icons class.
   uses-material-design: true
+  assets:
+    - assets/icon/app_icon.png
 
   # To add assets to your application, add an assets section, like this:
   # assets: