refine blocked user message, send users to blocks page instead of messages when username is available

lib/screens/settings/sections/auth_section.dart

@@ -40,10 +40,12 @@ class AuthSection extends StatelessWidget {
                   }
                 } else {
                   // Start login flow - the user will be redirected to browser
-                  await appState.forceLogin();
+                  await appState.forceLogin(context: context);
                   
-                  // Don't show immediate feedback - the UI will update automatically
-                  // when the OAuth callback completes and notifyListeners() is called
+                  // Don't show immediate feedback on success - the UI will update
+                  // automatically when the OAuth callback completes and
+                  // notifyListeners() is called. Failures are surfaced directly
+                  // by forceLogin() via a snackbar/dialog.
                 }
               },
             ),