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/Apply/IGenerationApplier.cs

@@ -0,0 +1,23 @@
+using ZB.MOM.WW.OtOpcUa.Configuration.Validation;
+
+namespace ZB.MOM.WW.OtOpcUa.Configuration.Apply;
+
+/// <summary>
+///     Applies a <see cref="GenerationDiff"/> to whatever backing runtime the node owns: the OPC UA
+///     address space, driver subscriptions, the local cache, etc. The Core project wires concrete
+///     callbacks into this via <see cref="ApplyCallbacks"/> so the Configuration project stays free
+///     of a Core/Server dependency (interface independence per decision #59).
+/// </summary>
+public interface IGenerationApplier
+{
+    Task<ApplyResult> ApplyAsync(DraftSnapshot? from, DraftSnapshot to, CancellationToken ct);
+}
+
+public sealed record ApplyResult(
+    bool Succeeded,
+    GenerationDiff Diff,
+    IReadOnlyList<string> Errors)
+{
+    public static ApplyResult Ok(GenerationDiff diff) => new(true, diff, []);
+    public static ApplyResult Fail(GenerationDiff diff, IReadOnlyList<string> errors) => new(false, diff, errors);
+}