Resolve IntegrationTests-022..024

IntegrationTests-022 (Conventions): ResolveRepositoryRoot now throws
InvalidOperationException when the walk exhausts without finding a root
marker, with a message naming the start directory, the expected markers
(src/, .git, *.sln, *.slnx), and the MXGATEWAY_LIVE_MXACCESS_WORKER_EXE
escape hatch. Replaces the silent fallback to
Directory.GetCurrentDirectory() that previously masked misconfiguration.
New regression test
ResolveRepositoryRoot_NoMarkers_ThrowsInvalidOperationExceptionNamingStartAndMarkers
in IntegrationTestEnvironmentTests asserts the throw and the message
contents. TDD red→green confirmed.

IntegrationTests-023 (Testing coverage): DashboardLdapLiveTests's
AuthenticateAsync_AdminInGwAdminGroup_Succeeds now asserts that the
authenticated principal carries a ClaimTypes.Role claim with value
DashboardRoles.Admin in addition to the existing LdapGroupClaimType
assertion. A regression in MapGroupsToRoles (returning an empty list or
missing the RDN fallback) would now surface here. Gated by
MXGATEWAY_RUN_LIVE_LDAP_TESTS.

IntegrationTests-024 (Conventions): Option (b) — extracted within
IntegrationTests. New file TestSupport/NullDashboardEventBroadcaster.cs
(public type, private ctor, singleton Instance). The inline class at
the bottom of WorkerLiveMxAccessSmokeTests is gone; the file now imports
the shared type. Matches the unit-test project's Tests-007 / Tests-021 /
Tests-025 pattern while keeping the two test projects independently
buildable (no shared test-helpers project crossing module boundaries).

Verification: dotnet build src/ZB.MOM.WW.MxGateway.IntegrationTests
clean; 19/19 integration tests passing (live MxAccess + LDAP + Galaxy).

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

src/ZB.MOM.WW.MxGateway.IntegrationTests/TestSupport/NullDashboardEventBroadcaster.cs

@@ -0,0 +1,31 @@
+using ZB.MOM.WW.MxGateway.Contracts.Proto;
+using ZB.MOM.WW.MxGateway.Server.Dashboard.Hubs;
+
+namespace ZB.MOM.WW.MxGateway.IntegrationTests.TestSupport;
+
+/// <summary>
+/// No-op <see cref="IDashboardEventBroadcaster"/> for integration tests that
+/// construct an <see cref="ZB.MOM.WW.MxGateway.Server.Grpc.EventStreamService"/>
+/// without exercising the dashboard SignalR fan-out. Singleton because the
+/// type holds no state — every consumer can share <see cref="Instance"/>.
+/// The unit-test project owns a parallel copy under
+/// <c>ZB.MOM.WW.MxGateway.Tests/TestSupport/</c>; IntegrationTests keeps its
+/// own copy here so the two test projects stay independently buildable
+/// without a shared test-helpers project (IntegrationTests-024).
+/// </summary>
+public sealed class NullDashboardEventBroadcaster : IDashboardEventBroadcaster
+{
+    /// <summary>Shared no-op instance.</summary>
+    public static readonly NullDashboardEventBroadcaster Instance = new();
+
+    private NullDashboardEventBroadcaster()
+    {
+    }
+
+    /// <inheritdoc />
+    public void Publish(string sessionId, MxEvent mxEvent)
+    {
+        // Intentionally empty — integration tests assert directly on the gRPC
+        // stream writer, not on dashboard fan-out.
+    }
+}