don't init UP on platforms other than Linux or Android

lib/controllers/unified_push.dart

@@ -21,6 +21,8 @@ import "package:window_manager/window_manager.dart";
 class UnifiedPushController extends AsyncNotifier<bool> {
   @override
   Future<bool> build() async {
+    if (Platform.isLinux ^ Platform.isAndroid) return false;
+
     final client = ref.watch(ClientController.provider.notifier);
     final registered = await UnifiedPush.initialize(
       linuxOptions: .new(

lib/controllers/unified_push_allowed.dart

@@ -8,11 +8,11 @@ class UnifiedPushAllowedController extends AsyncNotifier<String?> {
   @override
   Future<String?> build() async {
     if (!await UnifiedPush.tryUseCurrentOrDefaultDistributor()) {
-      return "No valid distributors found. Try installing ${Platform.isLinux
-          ? "KUnifiedPush"
+      return "No valid distributors found. ${Platform.isLinux
+          ? "Try installing KUnifiedPush"
           : Platform.isAndroid
-          ? "Google Play Services or NTFY"
-          : "NTFY"}.";
+          ? "Try installing Google Play Services or NTFY"
+          : "Your platform is not currently supported by UnifiedPush"}.";
     }
 
     final capabilities = await ref