fix(adminui): S7 typed page no longer wipes Tags on save

- S7DriverPage.FormModel now preserves Tags through Form ↔ Options
  translation (was hard-coding Tags = [] on every save, silently
  destroying any tag list that operators had configured).
- Add FormModel_RoundTrip tests for OpcUaClient and Historian
  mirror classes — both were translating Options ↔ form-model
  entirely untested.
- Surface S7 Tags in the round-trip test so this regression
  can't reach merge again.

tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/HistorianWonderwareDriverPageFormSerializationTests.cs

@@ -2,6 +2,7 @@ using System.Text.Json;
 using System.Text.Json.Serialization;
 using Shouldly;
 using Xunit;
+using ZB.MOM.WW.OtOpcUa.AdminUI.Components.Pages.Clusters.Drivers;
 using ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Client;
 
 namespace ZB.MOM.WW.OtOpcUa.AdminUI.Tests;
@@ -80,4 +81,32 @@ public sealed class HistorianWonderwareDriverPageFormSerializationTests
         back.ProbeTimeoutSeconds.ShouldBe(20);
         back.PipeName.ShouldBe("otopcua-historian");
     }
+
+    [Fact]
+    public void FormModel_RoundTrip_PreservesAllFields()
+    {
+        // Construct a record with non-default values for every property and verify
+        // that WonderwareHistorianClientFormModel.FromRecord → ToRecord is lossless.
+        var original = new WonderwareHistorianClientOptions(
+            PipeName: "otopcua-historian-prod",
+            SharedSecret: "sup3rs3cr3t",
+            PeerName: "OtOpcUa-Redundant",
+            ConnectTimeout: TimeSpan.FromSeconds(18),
+            CallTimeout: TimeSpan.FromSeconds(45))
+        {
+            ProbeTimeoutSeconds = 30,
+        };
+
+        var form = HistorianWonderwareDriverPage.WonderwareHistorianClientFormModel.FromRecord(original);
+        var result = form.ToRecord();
+
+        result.PipeName.ShouldBe("otopcua-historian-prod");
+        result.SharedSecret.ShouldBe("sup3rs3cr3t");
+        result.PeerName.ShouldBe("OtOpcUa-Redundant");
+        result.ConnectTimeout.ShouldBe(TimeSpan.FromSeconds(18));
+        result.CallTimeout.ShouldBe(TimeSpan.FromSeconds(45));
+        result.EffectiveConnectTimeout.ShouldBe(TimeSpan.FromSeconds(18));
+        result.EffectiveCallTimeout.ShouldBe(TimeSpan.FromSeconds(45));
+        result.ProbeTimeoutSeconds.ShouldBe(30);
+    }
 }