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.Core.Abstractions/IDriverSupervisor.cs

@@ -0,0 +1,26 @@
+namespace ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+/// <summary>
+///     Process-level supervisor contract a Tier C driver's out-of-process topology provides
+///     (e.g. <c>Driver.Galaxy.Proxy/Supervisor/</c>). Concerns: restart the Host process when a
+///     hard fault is detected (memory breach, wedge, scheduled recycle window).
+/// </summary>
+/// <remarks>
+///     Per <c>docs/v2/plan.md</c> decisions #68, #73-74, and #145. Tier A/B drivers do NOT have
+///     a supervisor because they run in-process — recycling would kill every OPC UA session and
+///     every co-hosted driver. The Core.Stability layer only invokes this interface for Tier C
+///     instances after asserting the tier via <see cref="DriverTypeMetadata.Tier"/>.
+/// </remarks>
+public interface IDriverSupervisor
+{
+    /// <summary>Driver instance this supervisor governs.</summary>
+    string DriverInstanceId { get; }
+
+    /// <summary>
+    ///     Request the supervisor to recycle (terminate + restart) the Host process. Implementations
+    ///     are expected to be idempotent under repeat calls during an in-flight recycle.
+    /// </summary>
+    /// <param name="reason">Human-readable reason — flows into the supervisor's logs.</param>
+    /// <param name="cancellationToken">Cancels the recycle request; an in-flight restart is not interrupted.</param>
+    Task RecycleAsync(string reason, CancellationToken cancellationToken);
+}