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/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware/Backend/IHistorianDataSource.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Backend
+{
+    /// <summary>
+    ///     OPC-UA-free surface for the Wonderware Historian subsystem inside Galaxy.Host.
+    ///     Implementations read via the aahClient* SDK; the Proxy side maps returned samples
+    ///     to OPC UA <c>DataValue</c>.
+    /// </summary>
+    public interface IHistorianDataSource : IDisposable
+    {
+        Task<List<HistorianSample>> ReadRawAsync(
+            string tagName, DateTime startTime, DateTime endTime, int maxValues,
+            CancellationToken ct = default);
+
+        Task<List<HistorianAggregateSample>> ReadAggregateAsync(
+            string tagName, DateTime startTime, DateTime endTime,
+            double intervalMs, string aggregateColumn,
+            CancellationToken ct = default);
+
+        Task<List<HistorianSample>> ReadAtTimeAsync(
+            string tagName, DateTime[] timestamps,
+            CancellationToken ct = default);
+
+        Task<List<HistorianEventDto>> ReadEventsAsync(
+            string? sourceName, DateTime startTime, DateTime endTime, int maxEvents,
+            CancellationToken ct = default);
+
+        HistorianHealthSnapshot GetHealthSnapshot();
+    }
+}