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>

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/App.axaml.cs

@@ -0,0 +1,33 @@
+using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Markup.Xaml;
+using ZB.MOM.WW.OtOpcUa.Client.Shared;
+using ZB.MOM.WW.OtOpcUa.Client.UI.Services;
+using ZB.MOM.WW.OtOpcUa.Client.UI.ViewModels;
+using ZB.MOM.WW.OtOpcUa.Client.UI.Views;
+
+namespace ZB.MOM.WW.OtOpcUa.Client.UI;
+
+public class App : Application
+{
+    public override void Initialize()
+    {
+        AvaloniaXamlLoader.Load(this);
+    }
+
+    public override void OnFrameworkInitializationCompleted()
+    {
+        if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+        {
+            var factory = new OpcUaClientServiceFactory();
+            var dispatcher = new AvaloniaUiDispatcher();
+            var viewModel = new MainWindowViewModel(factory, dispatcher);
+            desktop.MainWindow = new MainWindow
+            {
+                DataContext = viewModel
+            };
+        }
+
+        base.OnFrameworkInitializationCompleted();
+    }
+}