feat: update README and technical documentation with onboarding improvements, user experience enhancements, and architectural details

flutter/lib/core/ui/app_shell.dart

@@ -178,8 +178,6 @@ class AppShell extends ConsumerWidget {
                   if (location != '/profile' && context.mounted) {
                     context.go('/profile');
                   }
-                case 'logout':
-                  logout();
               }
             },
             itemBuilder: (context) => const [
@@ -191,14 +189,6 @@ class AppShell extends ConsumerWidget {
                   contentPadding: EdgeInsets.zero,
                 ),
               ),
-              PopupMenuItem<String>(
-                value: 'logout',
-                child: ListTile(
-                  leading: Icon(Icons.logout),
-                  title: Text('Logga ut'),
-                  contentPadding: EdgeInsets.zero,
-                ),
-              ),
             ],
           ),
         ],