feat: add standalone LmxProxy solution, windev VM documentation

Split LmxProxy Host and Client into a self-contained solution under lmxproxy/,
ported from the ScadaBridge monorepo with updated namespaces (ZB.MOM.WW.LmxProxy.*).
Client project (.NET 10) inlines Core/DataEngine dependencies and builds clean.
Host project (.NET Fx 4.8) retains ArchestrA.MXAccess for Windows deployment.
Added windev.md documenting the WW_DEV_VM development environment setup.

lmxproxy/src/ZB.MOM.WW.LmxProxy.Client/LmxProxyClient.ISubscription.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Threading.Tasks;
+
+namespace ZB.MOM.WW.LmxProxy.Client
+{
+    /// <summary>
+    /// Represents a subscription to tag value changes
+    /// </summary>
+    public interface ISubscription : IDisposable
+    {
+        /// <summary>
+        /// Disposes the subscription asynchronously
+        /// </summary>
+        Task DisposeAsync();
+    }
+}