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/Core/ZB.MOM.WW.OtOpcUa.Configuration/Enums/RedundancyMode.cs

@@ -0,0 +1,17 @@
+namespace ZB.MOM.WW.OtOpcUa.Configuration.Enums;
+
+/// <summary>
+///     Cluster redundancy mode per OPC UA Part 5 §6.5. Persisted as string in
+///     <c>ServerCluster.RedundancyMode</c> with a CHECK constraint coupling to <c>NodeCount</c>.
+/// </summary>
+public enum RedundancyMode
+{
+    /// <summary>Single-node cluster. Required when <c>NodeCount = 1</c>.</summary>
+    None,
+
+    /// <summary>Warm redundancy (non-transparent). Two-node cluster.</summary>
+    Warm,
+
+    /// <summary>Hot redundancy (non-transparent). Two-node cluster.</summary>
+    Hot,
+}