deprecate(lmxproxy): move all LmxProxy code, tests, and docs to deprecated/

LmxProxy is no longer needed. Moved the entire lmxproxy/ workspace, DCL
adapter files, and related docs to deprecated/. Removed LmxProxy registration
from DataConnectionFactory, project reference from DCL, protocol option from
UI, and cleaned up all requirement docs.

deprecated/lmxproxy/tests/ZB.MOM.WW.LmxProxy.Client.IntegrationTests/ConnectionTests.cs

@@ -0,0 +1,29 @@
+namespace ZB.MOM.WW.LmxProxy.Client.IntegrationTests;
+
+public class ConnectionTests : IntegrationTestBase
+{
+    [Fact]
+    public async Task ConnectAndDisconnect_Succeeds()
+    {
+        // Client is connected in InitializeAsync
+        Assert.True(await Client!.IsConnectedAsync());
+        await Client.DisconnectAsync();
+        Assert.False(await Client.IsConnectedAsync());
+    }
+
+    [Fact]
+    public async Task ConnectWithInvalidApiKey_Fails()
+    {
+        using var badClient = CreateClient(InvalidApiKey);
+        var ex = await Assert.ThrowsAsync<Grpc.Core.RpcException>(
+            () => badClient.ConnectAsync());
+        Assert.Equal(Grpc.Core.StatusCode.Unauthenticated, ex.StatusCode);
+    }
+
+    [Fact]
+    public async Task DoubleConnect_IsIdempotent()
+    {
+        await Client!.ConnectAsync(); // Already connected — should be no-op
+        Assert.True(await Client.IsConnectedAsync());
+    }
+}