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/DriverHostState.cs

@@ -0,0 +1,21 @@
+namespace ZB.MOM.WW.OtOpcUa.Configuration.Enums;
+
+/// <summary>
+///     Persisted mirror of <c>Core.Abstractions.HostState</c> — the lifecycle state each
+///     <c>IHostConnectivityProbe</c>-capable driver reports for its per-host topology
+///     (Galaxy Platforms / AppEngines, Modbus PLC endpoints, future OPC UA gateway upstreams).
+///     Defined here instead of re-using <c>Core.Abstractions.HostState</c> so the
+///     Configuration project stays free of driver-runtime dependencies.
+/// </summary>
+/// <remarks>
+///     The server-side publisher (follow-up PR) translates
+///     <c>HostStatusChangedEventArgs.NewState</c> to this enum on every transition and
+///     upserts into <see cref="Entities.DriverHostStatus"/>. Admin UI reads from the DB.
+/// </remarks>
+public enum DriverHostState
+{
+    Unknown,
+    Running,
+    Stopped,
+    Faulted,
+}