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/Drivers/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Tests/FakeTwinCATClient.cs

@@ -0,0 +1,132 @@
+using System.Runtime.CompilerServices;
+using ZB.MOM.WW.OtOpcUa.Driver.TwinCAT;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Tests;
+
+internal class FakeTwinCATClient : ITwinCATClient
+{
+    public bool IsConnected { get; private set; }
+    public int ConnectCount { get; private set; }
+    public int DisposeCount { get; private set; }
+    public bool ThrowOnConnect { get; set; }
+    public bool ThrowOnRead { get; set; }
+    public bool ThrowOnWrite { get; set; }
+    public bool ThrowOnProbe { get; set; }
+    public Exception? Exception { get; set; }
+    public Dictionary<string, object?> Values { get; } = new(StringComparer.OrdinalIgnoreCase);
+    public Dictionary<string, uint> ReadStatuses { get; } = new(StringComparer.OrdinalIgnoreCase);
+    public Dictionary<string, uint> WriteStatuses { get; } = new(StringComparer.OrdinalIgnoreCase);
+    public List<(string symbol, TwinCATDataType type, int? bit, object? value)> WriteLog { get; } = new();
+    public bool ProbeResult { get; set; } = true;
+
+    public virtual Task ConnectAsync(TwinCATAmsAddress address, TimeSpan timeout, CancellationToken ct)
+    {
+        ConnectCount++;
+        if (ThrowOnConnect) throw Exception ?? new InvalidOperationException();
+        IsConnected = true;
+        return Task.CompletedTask;
+    }
+
+    public virtual Task<(object? value, uint status)> ReadValueAsync(
+        string symbolPath, TwinCATDataType type, int? bitIndex, CancellationToken ct)
+    {
+        if (ThrowOnRead) throw Exception ?? new InvalidOperationException();
+        var status = ReadStatuses.TryGetValue(symbolPath, out var s) ? s : TwinCATStatusMapper.Good;
+        var value = Values.TryGetValue(symbolPath, out var v) ? v : null;
+        return Task.FromResult((value, status));
+    }
+
+    public virtual Task<uint> WriteValueAsync(
+        string symbolPath, TwinCATDataType type, int? bitIndex, object? value, CancellationToken ct)
+    {
+        if (ThrowOnWrite) throw Exception ?? new InvalidOperationException();
+        WriteLog.Add((symbolPath, type, bitIndex, value));
+        Values[symbolPath] = value;
+        var status = WriteStatuses.TryGetValue(symbolPath, out var s) ? s : TwinCATStatusMapper.Good;
+        return Task.FromResult(status);
+    }
+
+    public virtual Task<bool> ProbeAsync(CancellationToken ct)
+    {
+        if (ThrowOnProbe) return Task.FromResult(false);
+        return Task.FromResult(ProbeResult);
+    }
+
+    public virtual void Dispose()
+    {
+        DisposeCount++;
+        IsConnected = false;
+    }
+
+    // ---- notification fake ----
+
+    public List<FakeNotification> Notifications { get; } = new();
+    public bool ThrowOnAddNotification { get; set; }
+
+    public virtual Task<ITwinCATNotificationHandle> AddNotificationAsync(
+        string symbolPath, TwinCATDataType type, int? bitIndex, TimeSpan cycleTime,
+        Action<string, object?> onChange, CancellationToken cancellationToken)
+    {
+        if (ThrowOnAddNotification)
+            throw Exception ?? new InvalidOperationException("fake AddNotification failure");
+
+        var reg = new FakeNotification(symbolPath, type, bitIndex, onChange, this);
+        Notifications.Add(reg);
+        return Task.FromResult<ITwinCATNotificationHandle>(reg);
+    }
+
+    /// <summary>Fire a change event through the registered callback for <paramref name="symbolPath"/>.</summary>
+    public void FireNotification(string symbolPath, object? value)
+    {
+        foreach (var n in Notifications)
+            if (!n.Disposed && string.Equals(n.SymbolPath, symbolPath, StringComparison.OrdinalIgnoreCase))
+                n.OnChange(symbolPath, value);
+    }
+
+    // ---- symbol browser fake ----
+
+    public List<TwinCATDiscoveredSymbol> BrowseResults { get; } = new();
+    public bool ThrowOnBrowse { get; set; }
+
+    public virtual async IAsyncEnumerable<TwinCATDiscoveredSymbol> BrowseSymbolsAsync(
+        [EnumeratorCancellation] CancellationToken cancellationToken)
+    {
+        if (ThrowOnBrowse) throw Exception ?? new InvalidOperationException("fake browse failure");
+        await Task.CompletedTask;
+        foreach (var sym in BrowseResults)
+        {
+            if (cancellationToken.IsCancellationRequested) yield break;
+            yield return sym;
+        }
+    }
+
+    public sealed class FakeNotification(
+        string symbolPath, TwinCATDataType type, int? bitIndex,
+        Action<string, object?> onChange, FakeTwinCATClient owner) : ITwinCATNotificationHandle
+    {
+        public string SymbolPath { get; } = symbolPath;
+        public TwinCATDataType Type { get; } = type;
+        public int? BitIndex { get; } = bitIndex;
+        public Action<string, object?> OnChange { get; } = onChange;
+        public bool Disposed { get; private set; }
+
+        public void Dispose()
+        {
+            Disposed = true;
+            owner.Notifications.Remove(this);
+        }
+    }
+}
+
+internal sealed class FakeTwinCATClientFactory : ITwinCATClientFactory
+{
+    public List<FakeTwinCATClient> Clients { get; } = new();
+    public Func<FakeTwinCATClient>? Customise { get; set; }
+
+    public ITwinCATClient Create()
+    {
+        var client = Customise?.Invoke() ?? new FakeTwinCATClient();
+        Clients.Add(client);
+        return client;
+    }
+}