Add mux

lib/singbox/model/singbox_config_enum.dart

@@ -72,3 +72,9 @@ enum TunImplementation {
   system,
   gVisor;
 }
+
+enum MuxProtocol {
+  h2mux,
+  smux,
+  yamux;
+}

lib/singbox/model/singbox_config_option.dart

@@ -48,6 +48,10 @@ class SingboxConfigOption with _$SingboxConfigOption {
     required bool enableTlsPadding,
     @RangeWithOptionalCeilJsonConverter()
     required RangeWithOptionalCeil tlsPaddingSize,
+    required bool enableMux,
+    required bool muxPadding,
+    required int muxMaxStreams,
+    required MuxProtocol muxProtocol,
     required String geoipPath,
     required String geositePath,
     required List<SingboxRule> rules,