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/Server/ZB.MOM.WW.OtOpcUa.Admin/Services/ClusterService.cs

@@ -0,0 +1,28 @@
+using Microsoft.EntityFrameworkCore;
+using ZB.MOM.WW.OtOpcUa.Configuration;
+using ZB.MOM.WW.OtOpcUa.Configuration.Entities;
+
+namespace ZB.MOM.WW.OtOpcUa.Admin.Services;
+
+/// <summary>
+///     Cluster CRUD surface used by the Blazor pages. Writes go through stored procs in later
+///     phases; Phase 1 reads via EF Core directly (DENY SELECT on <c>dbo</c> schema means this
+///     service connects as a DB owner during dev — production swaps in a read-only view grant).
+/// </summary>
+public sealed class ClusterService(OtOpcUaConfigDbContext db)
+{
+    public Task<List<ServerCluster>> ListAsync(CancellationToken ct) =>
+        db.ServerClusters.AsNoTracking().OrderBy(c => c.ClusterId).ToListAsync(ct);
+
+    public Task<ServerCluster?> FindAsync(string clusterId, CancellationToken ct) =>
+        db.ServerClusters.AsNoTracking().FirstOrDefaultAsync(c => c.ClusterId == clusterId, ct);
+
+    public async Task<ServerCluster> CreateAsync(ServerCluster cluster, string createdBy, CancellationToken ct)
+    {
+        cluster.CreatedAt = DateTime.UtcNow;
+        cluster.CreatedBy = createdBy;
+        db.ServerClusters.Add(cluster);
+        await db.SaveChangesAsync(ct);
+        return cluster;
+    }
+}