Add android per-app proxy

lib/domain/singbox/rules.dart

@@ -0,0 +1,24 @@
+import 'package:hiddify/core/prefs/locale_prefs.dart';
+
+enum PerAppProxyMode {
+  off,
+  include,
+  exclude;
+
+  bool get enabled => this != off;
+
+  ({String title, String message}) present(TranslationsEn t) => switch (this) {
+        off => (
+            title: t.settings.network.perAppProxyModes.off,
+            message: t.settings.network.perAppProxyModes.offMsg,
+          ),
+        include => (
+            title: t.settings.network.perAppProxyModes.include,
+            message: t.settings.network.perAppProxyModes.includeMsg,
+          ),
+        exclude => (
+            title: t.settings.network.perAppProxyModes.exclude,
+            message: t.settings.network.perAppProxyModes.excludeMsg,
+          ),
+      };
+}

lib/domain/singbox/singbox.dart

@@ -2,4 +2,5 @@ export 'config_options.dart';
 export 'core_status.dart';
 export 'outbounds.dart';
 export 'proxy_type.dart';
+export 'rules.dart';
 export 'singbox_facade.dart';