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.FOCAS/Wire/FocasWireException.cs

@@ -0,0 +1,51 @@
+namespace ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Wire;
+
+/// <summary>
+///     Thrown by the wire client when a FOCAS request fails — either at the protocol layer
+///     (invalid PDU magic, desynchronised response framing, connection dropped mid-request)
+///     or when the CNC returns a non-zero <c>EW_*</c> return code.
+/// </summary>
+/// <remarks>
+///     <para>Callers distinguish the two classes via <see cref="IsTransient"/>: <c>true</c>
+///     when the transport is gone (socket closed, timeout, cancellation mid-write) and the
+///     wire client has already torn the sockets down, so a reconnect is required before any
+///     further call. <c>false</c> for protocol-level errors where the connection is still
+///     usable.</para>
+///     <para><see cref="Rc"/> carries the wire-level FOCAS return code when the exception
+///     came from a parsed response block. Null when the failure happened before a response
+///     was received (e.g. connect-time handshake errors).</para>
+/// </remarks>
+public class FocasWireException : Exception
+{
+    /// <summary>FOCAS <c>EW_*</c> return code from the response block, when available.</summary>
+    public short? Rc { get; }
+
+    /// <summary>
+    ///     True when the transport was closed as a side effect of this failure — the caller
+    ///     must reconnect before issuing the next request.
+    /// </summary>
+    public bool IsTransient { get; }
+
+    public FocasWireException(string message)
+        : base(message)
+    {
+    }
+
+    public FocasWireException(string message, short? rc, bool isTransient = false)
+        : base(message)
+    {
+        Rc = rc;
+        IsTransient = isTransient;
+    }
+
+    public FocasWireException(string message, Exception innerException)
+        : base(message, innerException)
+    {
+    }
+
+    public FocasWireException(string message, Exception innerException, bool isTransient)
+        : base(message, innerException)
+    {
+        IsTransient = isTransient;
+    }
+}