fix: opdate InstallAlertDialog to conditionally display "Always trust" switch based on user sign-in status

lib/widgets/install_alert_dialog.dart

@@ -84,6 +84,8 @@ class InstallAlertDialog extends HookConsumerWidget {
                       ),
                     ],
                   ),
+            // Only show "Always trust" when signed in (requires signer to persist)
+            if (profile != null) ...[
               const Gap(14),
               Row(
                 crossAxisAlignment: CrossAxisAlignment.center,
@@ -117,6 +119,7 @@ class InstallAlertDialog extends HookConsumerWidget {
               ),
             ],
           ],
+        ],
       ),
       actions: [
         TextButton(