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/ViewModels/BrowseTreeViewModel.cs

@@ -0,0 +1,53 @@
+using System.Collections.ObjectModel;
+using CommunityToolkit.Mvvm.ComponentModel;
+using ZB.MOM.WW.OtOpcUa.Client.Shared;
+using ZB.MOM.WW.OtOpcUa.Client.UI.Services;
+
+namespace ZB.MOM.WW.OtOpcUa.Client.UI.ViewModels;
+
+/// <summary>
+///     ViewModel for the OPC UA browse tree panel.
+/// </summary>
+public class BrowseTreeViewModel : ObservableObject
+{
+    private readonly IUiDispatcher _dispatcher;
+    private readonly IOpcUaClientService _service;
+
+    public BrowseTreeViewModel(IOpcUaClientService service, IUiDispatcher dispatcher)
+    {
+        _service = service;
+        _dispatcher = dispatcher;
+    }
+
+    /// <summary>Top-level nodes in the browse tree.</summary>
+    public ObservableCollection<TreeNodeViewModel> RootNodes { get; } = [];
+
+    /// <summary>
+    ///     Loads root nodes by browsing with a null parent.
+    /// </summary>
+    public async Task LoadRootsAsync()
+    {
+        var results = await _service.BrowseAsync();
+
+        _dispatcher.Post(() =>
+        {
+            RootNodes.Clear();
+            foreach (var result in results)
+                RootNodes.Add(new TreeNodeViewModel(
+                    result.NodeId,
+                    result.DisplayName,
+                    result.NodeClass,
+                    result.HasChildren,
+                    _service,
+                    _dispatcher));
+        });
+    }
+
+    /// <summary>
+    ///     Clears all root nodes from the tree.
+    /// </summary>
+    public void Clear()
+    {
+        RootNodes.Clear();
+    }
+}