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/Fakes/FakeSessionFactory.cs

@@ -0,0 +1,52 @@
+using Opc.Ua;
+using ZB.MOM.WW.OtOpcUa.Client.Shared.Adapters;
+
+namespace ZB.MOM.WW.OtOpcUa.Client.Shared.Tests.Fakes;
+
+internal sealed class FakeSessionFactory : ISessionFactory
+{
+    private readonly List<FakeSessionAdapter> _createdSessions = [];
+    private readonly Queue<FakeSessionAdapter> _sessions = new();
+
+    public int CreateCallCount { get; private set; }
+    public bool ThrowOnCreate { get; set; }
+    public string? LastEndpointUrl { get; private set; }
+
+    public IReadOnlyList<FakeSessionAdapter> CreatedSessions => _createdSessions;
+
+    public Task<ISessionAdapter> CreateSessionAsync(
+        ApplicationConfiguration config, EndpointDescription endpoint, string sessionName,
+        uint sessionTimeoutMs, UserIdentity identity, CancellationToken ct)
+    {
+        CreateCallCount++;
+        LastEndpointUrl = endpoint.EndpointUrl;
+
+        if (ThrowOnCreate)
+            throw new InvalidOperationException("FakeSessionFactory configured to fail.");
+
+        FakeSessionAdapter session;
+        if (_sessions.Count > 0)
+            session = _sessions.Dequeue();
+        else
+            session = new FakeSessionAdapter
+            {
+                EndpointUrl = endpoint.EndpointUrl,
+                ServerName = endpoint.Server?.ApplicationName?.Text ?? "FakeServer",
+                SecurityMode = endpoint.SecurityMode.ToString(),
+                SecurityPolicyUri = endpoint.SecurityPolicyUri ?? string.Empty
+            };
+
+        // Ensure endpoint URL matches
+        session.EndpointUrl = endpoint.EndpointUrl;
+        _createdSessions.Add(session);
+        return Task.FromResult<ISessionAdapter>(session);
+    }
+
+    /// <summary>
+    ///     Enqueues a session adapter to be returned on the next call to CreateSessionAsync.
+    /// </summary>
+    public void EnqueueSession(FakeSessionAdapter session)
+    {
+        _sessions.Enqueue(session);
+    }
+}