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/Helpers/SecurityModeMapperTests.cs

@@ -0,0 +1,58 @@
+using Opc.Ua;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Helpers;
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Models;
+
+namespace ZB.MOM.WW.OtOpcUa.Client.Shared.Tests.Helpers;
+
+public class SecurityModeMapperTests
+{
+    [Theory]
+    [InlineData(SecurityMode.None, MessageSecurityMode.None)]
+    [InlineData(SecurityMode.Sign, MessageSecurityMode.Sign)]
+    [InlineData(SecurityMode.SignAndEncrypt, MessageSecurityMode.SignAndEncrypt)]
+    public void ToMessageSecurityMode_MapsCorrectly(SecurityMode input, MessageSecurityMode expected)
+    {
+        SecurityModeMapper.ToMessageSecurityMode(input).ShouldBe(expected);
+    }
+
+    [Fact]
+    public void ToMessageSecurityMode_InvalidValue_Throws()
+    {
+        Should.Throw<ArgumentOutOfRangeException>(() =>
+            SecurityModeMapper.ToMessageSecurityMode((SecurityMode)99));
+    }
+
+    [Theory]
+    [InlineData("none", SecurityMode.None)]
+    [InlineData("None", SecurityMode.None)]
+    [InlineData("NONE", SecurityMode.None)]
+    [InlineData("sign", SecurityMode.Sign)]
+    [InlineData("Sign", SecurityMode.Sign)]
+    [InlineData("encrypt", SecurityMode.SignAndEncrypt)]
+    [InlineData("signandencrypt", SecurityMode.SignAndEncrypt)]
+    [InlineData("SignAndEncrypt", SecurityMode.SignAndEncrypt)]
+    public void FromString_ParsesCorrectly(string input, SecurityMode expected)
+    {
+        SecurityModeMapper.FromString(input).ShouldBe(expected);
+    }
+
+    [Fact]
+    public void FromString_WithWhitespace_ParsesCorrectly()
+    {
+        SecurityModeMapper.FromString("  sign  ").ShouldBe(SecurityMode.Sign);
+    }
+
+    [Fact]
+    public void FromString_UnknownValue_Throws()
+    {
+        Should.Throw<ArgumentException>(() => SecurityModeMapper.FromString("invalid"));
+    }
+
+    [Fact]
+    public void FromString_Null_DefaultsToNone()
+    {
+        SecurityModeMapper.FromString(null!).ShouldBe(SecurityMode.None);
+    }
+}