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/Validation/DraftSnapshot.cs

@@ -0,0 +1,28 @@
+using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+
+namespace ZB.MOM.WW.OtOpcUa.Configuration.Validation;
+
+/// <summary>
+///     Inputs for draft validation. Contains the draft's rows plus the minimum prior-generation
+///     rows needed for cross-generation invariants (EquipmentUuid stability, UnsArea identity).
+/// </summary>
+public sealed class DraftSnapshot
+{
+    public required long GenerationId { get; init; }
+    public required string ClusterId { get; init; }
+
+    public IReadOnlyList<Namespace> Namespaces { get; init; } = [];
+    public IReadOnlyList<DriverInstance> DriverInstances { get; init; } = [];
+    public IReadOnlyList<Device> Devices { get; init; } = [];
+    public IReadOnlyList<UnsArea> UnsAreas { get; init; } = [];
+    public IReadOnlyList<UnsLine> UnsLines { get; init; } = [];
+    public IReadOnlyList<Equipment> Equipment { get; init; } = [];
+    public IReadOnlyList<Tag> Tags { get; init; } = [];
+    public IReadOnlyList<PollGroup> PollGroups { get; init; } = [];
+
+    /// <summary>Prior Equipment rows (any generation, same cluster) for stability checks.</summary>
+    public IReadOnlyList<Equipment> PriorEquipment { get; init; } = [];
+
+    /// <summary>Active reservations (<c>ReleasedAt IS NULL</c>) for pre-flight.</summary>
+    public IReadOnlyList<ExternalIdReservation> ActiveReservations { get; init; } = [];
+}