chore: organize solution into module folders (Core/Server/Drivers/Client/Tooling)

Group all 69 projects into category subfolders under src/ and tests/ so the
Rider Solution Explorer mirrors the module structure. Folders: Core, Server,
Drivers (with a nested Driver CLIs subfolder), Client, Tooling.

- Move every project folder on disk with git mv (history preserved as renames).
- Recompute relative paths in 57 .csproj files: cross-category ProjectReferences,
  the lib/ HintPath+None refs in Driver.Historian.Wonderware, and the external
  mxaccessgw refs in Driver.Galaxy and its test project.
- Rebuild ZB.MOM.WW.OtOpcUa.slnx with nested solution folders.
- Re-prefix project paths in functional scripts (e2e, compliance, smoke SQL,
  integration, install).

Build green (0 errors); unit tests pass. Docs left for a separate pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Models/ConnectionSettingsTests.cs

@@ -0,0 +1,95 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Models;
+
+namespace ZB.MOM.WW.OtOpcUa.Client.Shared.Tests.Models;
+
+public class ConnectionSettingsTests
+{
+    [Fact]
+    public void Defaults_AreCorrect()
+    {
+        var settings = new ConnectionSettings();
+
+        settings.EndpointUrl.ShouldBe(string.Empty);
+        settings.FailoverUrls.ShouldBeNull();
+        settings.Username.ShouldBeNull();
+        settings.Password.ShouldBeNull();
+        settings.SecurityMode.ShouldBe(SecurityMode.None);
+        settings.SessionTimeoutSeconds.ShouldBe(60);
+        settings.AutoAcceptCertificates.ShouldBeTrue();
+        settings.CertificateStorePath.ShouldContain("OtOpcUaClient");
+        settings.CertificateStorePath.ShouldContain("pki");
+    }
+
+    [Fact]
+    public void Validate_ThrowsOnNullEndpointUrl()
+    {
+        var settings = new ConnectionSettings { EndpointUrl = null! };
+        Should.Throw<ArgumentException>(() => settings.Validate())
+            .ParamName.ShouldBe("EndpointUrl");
+    }
+
+    [Fact]
+    public void Validate_ThrowsOnEmptyEndpointUrl()
+    {
+        var settings = new ConnectionSettings { EndpointUrl = "" };
+        Should.Throw<ArgumentException>(() => settings.Validate())
+            .ParamName.ShouldBe("EndpointUrl");
+    }
+
+    [Fact]
+    public void Validate_ThrowsOnWhitespaceEndpointUrl()
+    {
+        var settings = new ConnectionSettings { EndpointUrl = "   " };
+        Should.Throw<ArgumentException>(() => settings.Validate())
+            .ParamName.ShouldBe("EndpointUrl");
+    }
+
+    [Fact]
+    public void Validate_ThrowsOnZeroTimeout()
+    {
+        var settings = new ConnectionSettings
+        {
+            EndpointUrl = "opc.tcp://localhost:4840",
+            SessionTimeoutSeconds = 0
+        };
+        Should.Throw<ArgumentException>(() => settings.Validate())
+            .ParamName.ShouldBe("SessionTimeoutSeconds");
+    }
+
+    [Fact]
+    public void Validate_ThrowsOnNegativeTimeout()
+    {
+        var settings = new ConnectionSettings
+        {
+            EndpointUrl = "opc.tcp://localhost:4840",
+            SessionTimeoutSeconds = -1
+        };
+        Should.Throw<ArgumentException>(() => settings.Validate())
+            .ParamName.ShouldBe("SessionTimeoutSeconds");
+    }
+
+    [Fact]
+    public void Validate_ThrowsOnTimeoutAbove3600()
+    {
+        var settings = new ConnectionSettings
+        {
+            EndpointUrl = "opc.tcp://localhost:4840",
+            SessionTimeoutSeconds = 3601
+        };
+        Should.Throw<ArgumentException>(() => settings.Validate())
+            .ParamName.ShouldBe("SessionTimeoutSeconds");
+    }
+
+    [Fact]
+    public void Validate_SucceedsWithValidSettings()
+    {
+        var settings = new ConnectionSettings
+        {
+            EndpointUrl = "opc.tcp://localhost:4840",
+            SessionTimeoutSeconds = 120
+        };
+        Should.NotThrow(() => settings.Validate());
+    }
+}