PR 4.0 — Driver.Galaxy project skeleton + factory

New in-process .NET 10 driver project at
src/ZB.MOM.WW.OtOpcUa.Driver.Galaxy/. The Tier-A replacement for
Driver.Galaxy.Host + Driver.Galaxy.Proxy. PR 4.0 ships only the IDriver
shape + factory + options; capability bodies (browse, read, write,
subscribe, deploy-watch, host probes) land in PRs 4.1–4.7.

Files:
- Driver.Galaxy.csproj — net10 x64, AnyCPU+x64 platforms, references
  Core.Abstractions + Core. No MxGatewayClient ProjectReference yet — that
  comes in PR 4.2 once the gw NuGet package is wired (the user is
  shipping mxaccessgw on a parallel track).
- Config/GalaxyDriverOptions.cs — nested record hierarchy
  (Gateway/MxAccess/Repository/Reconnect) mirroring the JSON shape spelled
  out in lmx_mxgw_impl.md PR 4.0 acceptance section.
- GalaxyDriver.cs — minimal IDriver impl. Initialize/Shutdown toggle
  DriverHealth between Healthy/Unknown; Reinitialize bumps the timestamp;
  GetMemoryFootprint=0 (PR 4.4 wires SubscriptionRegistry size);
  FlushOptionalCachesAsync no-op. Logs intent on lifecycle calls so
  partial deployments are diagnosable.
- GalaxyDriverFactoryExtensions.cs — JSON parser, default fill-ins,
  validation throw on missing required fields. Driver type name
  "GalaxyMxGateway" intentionally distinct from legacy "Galaxy" so both
  factories coexist during parity testing (Phase 5). PR 4.W's
  Galaxy:Backend switch picks one or the other.

Tests:
- 10 tests in Driver.Galaxy.Tests covering minimal-config defaults, full
  override path, three required-field error cases, factory registration
  via DriverFactoryRegistry.TryGet, lifecycle health transitions
  (Init → Shutdown → Reinit), Dispose idempotency, and post-disposal
  ObjectDisposedException.

slnx: registers the new Driver.Galaxy + Driver.Galaxy.Tests projects.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ZB.MOM.WW.OtOpcUa.Driver.Galaxy/GalaxyDriver.cs

@@ -0,0 +1,102 @@
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Config;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy;
+
+/// <summary>
+///     In-process .NET 10 Galaxy driver — the v2 replacement for the Galaxy.Host /
+///     Galaxy.Proxy pair. PR 4.0 ships the project skeleton with <see cref="IDriver"/>
+///     bodies that wire to a future <c>IGalaxyGatewayClient</c> abstraction. Capability
+///     interfaces (browse, read, write, subscribe, history routing, host probes) land in
+///     PRs 4.1–4.7; the wiring sequence keeps every intermediate state buildable so the
+///     <c>Galaxy:Backend</c> flag (PR 4.W) can flip between legacy-host and mxgateway
+///     for parity testing.
+/// </summary>
+/// <remarks>
+///     This driver is registered as a Tier A in-process driver alongside Modbus / S7 / etc.
+///     The legacy <c>GalaxyProxyDriver</c> (Driver.Galaxy.Proxy) coexists until PR 7.2;
+///     <see cref="GalaxyDriverFactoryExtensions"/> registers under driver-type name
+///     "GalaxyMxGateway" so both paths can be live simultaneously during parity testing.
+/// </remarks>
+public sealed class GalaxyDriver : IDriver, IDisposable
+{
+    private readonly string _driverInstanceId;
+    private readonly GalaxyDriverOptions _options;
+    private readonly ILogger<GalaxyDriver> _logger;
+
+    private DriverHealth _health = new(DriverState.Unknown, null, null);
+    private bool _disposed;
+
+    public GalaxyDriver(
+        string driverInstanceId,
+        GalaxyDriverOptions options,
+        ILogger<GalaxyDriver>? logger = null)
+    {
+        _driverInstanceId = !string.IsNullOrWhiteSpace(driverInstanceId)
+            ? driverInstanceId
+            : throw new ArgumentException("Driver instance id required.", nameof(driverInstanceId));
+        _options = options ?? throw new ArgumentNullException(nameof(options));
+        _logger = logger ?? NullLogger<GalaxyDriver>.Instance;
+    }
+
+    /// <inheritdoc />
+    public string DriverInstanceId => _driverInstanceId;
+
+    /// <inheritdoc />
+    public string DriverType => GalaxyDriverFactoryExtensions.DriverTypeName;
+
+    /// <summary>Test-visible options snapshot.</summary>
+    internal GalaxyDriverOptions Options => _options;
+
+    /// <inheritdoc />
+    public Task InitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
+    {
+        ObjectDisposedException.ThrowIf(_disposed, this);
+
+        // PR 4.0 skeleton — capability bodies (PRs 4.1-4.7) replace this stub with real
+        // MxGatewayClient session opening. The skeleton keeps the IDriver shape buildable
+        // so the Galaxy:Backend flag (PR 4.W) can register the driver factory now.
+        _logger.LogInformation(
+            "GalaxyDriver {InstanceId} initializing — endpoint={Endpoint} clientName={ClientName} (skeleton; real gateway connect in PR 4.1+)",
+            _driverInstanceId, _options.Gateway.Endpoint, _options.MxAccess.ClientName);
+        _health = new DriverHealth(DriverState.Healthy, DateTime.UtcNow, null);
+        return Task.CompletedTask;
+    }
+
+    /// <inheritdoc />
+    public Task ReinitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
+    {
+        // In-place config reapply. PR 4.5's reconnect supervisor will swap the
+        // gateway-client options under the lock; for the skeleton we just refresh health.
+        ObjectDisposedException.ThrowIf(_disposed, this);
+        _health = new DriverHealth(DriverState.Healthy, DateTime.UtcNow, null);
+        return Task.CompletedTask;
+    }
+
+    /// <inheritdoc />
+    public Task ShutdownAsync(CancellationToken cancellationToken)
+    {
+        if (_disposed) return Task.CompletedTask;
+        _logger.LogInformation("GalaxyDriver {InstanceId} shutting down", _driverInstanceId);
+        _health = new DriverHealth(DriverState.Unknown, _health.LastSuccessfulRead, null);
+        return Task.CompletedTask;
+    }
+
+    /// <inheritdoc />
+    public DriverHealth GetHealth() => _health;
+
+    /// <inheritdoc />
+    public long GetMemoryFootprint() => 0; // PR 4.4 sets this from SubscriptionRegistry size.
+
+    /// <inheritdoc />
+    public Task FlushOptionalCachesAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+
+    public void Dispose()
+    {
+        if (_disposed) return;
+        _disposed = true;
+        // No owned IDisposables until PR 4.2's GalaxyMxSession lands.
+    }
+}