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.Host/Domain/SubscriptionStats.cs

@@ -0,0 +1,30 @@
+using System.Collections.Generic;
+
+namespace ZB.MOM.WW.LmxProxy.Host.Domain
+{
+    /// <summary>
+    ///     Subscription statistics for all clients and tags.
+    /// </summary>
+    public class SubscriptionStats
+    {
+        /// <summary>
+        ///     Gets or sets the total number of clients.
+        /// </summary>
+        public int TotalClients { get; set; }
+
+        /// <summary>
+        ///     Gets or sets the total number of tags.
+        /// </summary>
+        public int TotalTags { get; set; }
+
+        /// <summary>
+        ///     Gets or sets the mapping of tag addresses to client counts.
+        /// </summary>
+        public Dictionary<string, int> TagClientCounts { get; set; } = new();
+
+        /// <summary>
+        ///     Gets or sets the mapping of client IDs to their statistics.
+        /// </summary>
+        public Dictionary<string, ClientStats> ClientStats { get; set; } = new();
+    }
+}