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/DesignTimeDbContextFactory.cs

@@ -0,0 +1,28 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Design;
+
+namespace ZB.MOM.WW.OtOpcUa.Configuration;
+
+/// <summary>
+///     Used by <c>dotnet ef</c> at design time (migrations, scaffolding). Reads the connection string
+///     from the <c>OTOPCUA_CONFIG_CONNECTION</c> environment variable, falling back to the local dev
+///     container on <c>localhost:1433</c>.
+/// </summary>
+public sealed class DesignTimeDbContextFactory : IDesignTimeDbContextFactory<OtOpcUaConfigDbContext>
+{
+    // Host-port 14330 avoids collision with the native MSSQL14 instance on 1433 (Galaxy "ZB" DB).
+    private const string DefaultConnectionString =
+        "Server=localhost,14330;Database=OtOpcUaConfig;User Id=sa;Password=OtOpcUaDev_2026!;TrustServerCertificate=True;Encrypt=False;";
+
+    public OtOpcUaConfigDbContext CreateDbContext(string[] args)
+    {
+        var connection = Environment.GetEnvironmentVariable("OTOPCUA_CONFIG_CONNECTION")
+                         ?? DefaultConnectionString;
+
+        var options = new DbContextOptionsBuilder<OtOpcUaConfigDbContext>()
+            .UseSqlServer(connection, sql => sql.MigrationsAssembly(typeof(OtOpcUaConfigDbContext).Assembly.FullName))
+            .Options;
+
+        return new OtOpcUaConfigDbContext(options);
+    }
+}