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/HistorianSample.cs

@@ -0,0 +1,30 @@
+using System;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Backend
+{
+    /// <summary>
+    ///     OPC-UA-free representation of a single historical data point. The Host returns these
+    ///     across the IPC boundary as <c>GalaxyDataValue</c>; the Proxy maps quality and value to
+    ///     OPC UA <c>DataValue</c>. Raw MX quality byte is preserved so the Proxy can use the same
+    ///     quality mapper it already uses for live reads.
+    /// </summary>
+    public sealed class HistorianSample
+    {
+        public object? Value { get; set; }
+
+        /// <summary>Raw OPC DA quality byte from the historian SDK (low 8 bits of OpcQuality).</summary>
+        public byte Quality { get; set; }
+
+        public DateTime TimestampUtc { get; set; }
+    }
+
+    /// <summary>
+    ///     Result of <see cref="IHistorianDataSource.ReadAggregateAsync"/>. When <see cref="Value"/> is
+    ///     null the aggregate is unavailable for that bucket (Proxy maps to <c>BadNoData</c>).
+    /// </summary>
+    public sealed class HistorianAggregateSample
+    {
+        public double? Value { get; set; }
+        public DateTime TimestampUtc { get; set; }
+    }
+}