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.Worker/MxAccess/IAlarmCommandHandler.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+using ZB.MOM.WW.MxGateway.Contracts.Proto;
+
+namespace ZB.MOM.WW.MxGateway.Worker.MxAccess;
+
+/// <summary>
+///     Per-session interface routing the worker's alarm IPC commands —
+///     <c>SubscribeAlarmsCommand</c>, <c>AcknowledgeAlarmCommand</c>,
+///     <c>QueryActiveAlarmsCommand</c>, <c>UnsubscribeAlarmsCommand</c> —
+///     to the underlying <see cref="AlarmDispatcher"/>. Production binding
+///     is <see cref="AlarmCommandHandler"/>; tests substitute a fake.
+/// </summary>
+public interface IAlarmCommandHandler : IDisposable
+{
+    /// <summary>Begin a subscription against the supplied AVEVA alarm-provider expression.</summary>
+    void Subscribe(string subscription, string sessionId);
+
+    /// <summary>Tear down the active subscription. No-op if not subscribed.</summary>
+    void Unsubscribe();
+
+    /// <summary>Acknowledge a single alarm by GUID. Returns AVEVA's native status (0 = success).</summary>
+    int Acknowledge(
+        Guid alarmGuid,
+        string comment,
+        string operatorUser,
+        string operatorNode,
+        string operatorDomain,
+        string operatorFullName);
+
+    /// <summary>
+    ///     Acknowledge a single alarm by (name, provider, group) — used when
+    ///     the caller has the human-readable reference but not the GUID.
+    /// </summary>
+    int AcknowledgeByName(
+        string alarmName,
+        string providerName,
+        string groupName,
+        string comment,
+        string operatorUser,
+        string operatorNode,
+        string operatorDomain,
+        string operatorFullName);
+
+    /// <summary>
+    ///     Snapshot the currently-active alarm set, optionally scoped to a
+    ///     prefix matched against <c>AlarmFullReference</c>.
+    /// </summary>
+    IReadOnlyList<ActiveAlarmSnapshot> QueryActive(string? alarmFilterPrefix);
+
+    /// <summary>
+    ///     Drives a single poll of the underlying alarm consumer on the
+    ///     caller's thread. This is a no-op when there is no active
+    ///     subscription. In production the caller is the worker's STA
+    ///     (marshalled via <c>StaRuntime.InvokeAsync</c>), which satisfies
+    ///     the <c>ThreadingModel=Apartment</c> requirement of
+    ///     <c>wwAlarmConsumerClass</c>.
+    /// </summary>
+    void PollOnce();
+}