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.Galaxy/Runtime/IGalaxySubscriber.cs

@@ -0,0 +1,32 @@
+using MxGateway.Contracts.Proto;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Runtime;
+
+/// <summary>
+///     Driver-side seam for subscription lifecycle + the inbound event stream. Production
+///     wraps <c>MxGatewaySession.SubscribeBulkAsync</c>, <c>UnsubscribeBulkAsync</c>, and
+///     <c>StreamEventsAsync</c>; tests substitute a fake to drive synthetic events through
+///     the <see cref="EventPump"/> without a real gw.
+/// </summary>
+public interface IGalaxySubscriber
+{
+    /// <summary>
+    ///     Subscribe a batch of tag full references. Returns one
+    ///     <see cref="SubscribeResult"/> per request entry, in input order. Failed tags
+    ///     (gateway rejection) carry a non-zero status and an item handle of zero or
+    ///     negative — the caller treats those as per-tag failures rather than a whole-call
+    ///     failure.
+    /// </summary>
+    Task<IReadOnlyList<SubscribeResult>> SubscribeBulkAsync(
+        IReadOnlyList<string> fullReferences, int bufferedUpdateIntervalMs, CancellationToken cancellationToken);
+
+    /// <summary>Unsubscribe a batch of item handles obtained from <see cref="SubscribeBulkAsync"/>.</summary>
+    Task UnsubscribeBulkAsync(IReadOnlyList<int> itemHandles, CancellationToken cancellationToken);
+
+    /// <summary>
+    ///     Long-running consumer of the gateway's <c>StreamEvents</c> RPC. Each emitted
+    ///     <see cref="MxEvent"/> carries the gw item handle the caller correlates against
+    ///     its <see cref="SubscriptionRegistry"/>.
+    /// </summary>
+    IAsyncEnumerable<MxEvent> StreamEventsAsync(CancellationToken cancellationToken);
+}