rename: prefix gateway projects/namespaces with ZB.MOM.WW + sln→slnx

Apply the ZB.MOM.WW. prefix to all gateway-side projects, folders,
.csproj/.sln contents, C# namespaces, using directives, generated proto
C# (csharp_namespace + checked-in generated files), InternalsVisibleTo
attributes, project-name string literals (LoadProject, .sln lookups,
worker exe paths, staticwebassets manifest), and the install/script/doc
references that point at any of the above. Migrate the solution from
.sln to .slnx via `dotnet sln migrate` and delete the old file.

External-runtime identifiers are intentionally NOT prefixed so external
configuration keeps working:
- GatewayMetrics.cs MeterName ("MxGateway.Server")
- DashboardAuthenticationDefaults Scheme/Policy ("MxGateway.Dashboard")
- GatewayRequestLoggingMiddleware logger category ("MxGateway.Request")
- StaRuntime thread name ("MxGateway.Worker.STA")
- appsettings.json root section "MxGateway" + env-var prefix
  MxGateway__... and secret-name MxGateway:ApiKeyPepper
- C:\ProgramData\MxGateway\ data dir paths

Also fixes two tests that were not rename-related but became visible
while validating the rename:

- WorkerLiveMxAccessSmokeTests.ShutDownAsync: cancellation that the
  gateway service correctly maps to RpcException(Cancelled) per gRPC
  convention was being misclassified as a stream fault. Added a sibling
  catch on RpcException with StatusCode.Cancelled.

- IntegrationTestEnvironment.ResolveRepositoryRoot: extracted IsRepositoryRoot
  and made it accept either a .git marker OR a .sln/.slnx next to src/
  so the worker-exe walker works in non-git working copies.

clients/proto/proto-inputs.json's protoRoot updated to point at
src/ZB.MOM.WW.MxGateway.Contracts/Protos.

Verified by `dotnet build` and a full `dotnet test` of the .slnx with
MXGATEWAY_RUN_LIVE_{MXACCESS,LDAP,GALAXY}_TESTS=1:
  Tests: 472/472 pass
  Worker.Tests: 280/280 pass (4 dev-rig [Fact(Skip=...)] skipped)
  IntegrationTests: 18/18 pass

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

src/ZB.MOM.WW.MxGateway.Tests/TestSupport/FakeGatewayAlarmService.cs

@@ -0,0 +1,54 @@
+using System.Runtime.CompilerServices;
+using ZB.MOM.WW.MxGateway.Contracts.Proto;
+using ZB.MOM.WW.MxGateway.Server.Alarms;
+
+namespace ZB.MOM.WW.MxGateway.Tests.TestSupport;
+
+/// <summary>
+///     <see cref="IGatewayAlarmService"/> test double — serves a scripted
+///     active-alarm set and acknowledges every request with an OK status,
+///     so gRPC service tests can exercise the alarm handlers without the
+///     real gateway alarm monitor or a worker.
+/// </summary>
+public sealed class FakeGatewayAlarmService : IGatewayAlarmService
+{
+    /// <inheritdoc />
+    public GatewayAlarmMonitorState State { get; set; } = GatewayAlarmMonitorState.Monitoring;
+
+    /// <inheritdoc />
+    public string? LastError { get; set; }
+
+    /// <inheritdoc />
+    public int? WorkerProcessId { get; set; }
+
+    /// <inheritdoc />
+    public IReadOnlyList<ActiveAlarmSnapshot> CurrentAlarms { get; set; } = [];
+
+    /// <inheritdoc />
+    public async IAsyncEnumerable<AlarmFeedMessage> StreamAsync(
+        string? alarmFilterPrefix,
+        [EnumeratorCancellation] CancellationToken cancellationToken)
+    {
+        foreach (ActiveAlarmSnapshot alarm in CurrentAlarms)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            yield return new AlarmFeedMessage { ActiveAlarm = alarm };
+        }
+
+        yield return new AlarmFeedMessage { SnapshotComplete = true };
+        await Task.CompletedTask.ConfigureAwait(false);
+    }
+
+    /// <inheritdoc />
+    public Task<AcknowledgeAlarmReply> AcknowledgeAsync(
+        AcknowledgeAlarmRequest request,
+        CancellationToken cancellationToken)
+    {
+        return Task.FromResult(new AcknowledgeAlarmReply
+        {
+            CorrelationId = request.ClientCorrelationId,
+            ProtocolStatus = new ProtocolStatus { Code = ProtocolStatusCode.Ok },
+            DiagnosticMessage = string.Empty,
+        });
+    }
+}