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/DashboardLdapLiveTests.cs

@@ -26,6 +26,16 @@ public sealed class DashboardLdapLiveTests
         Assert.Contains(result.Principal.Claims, claim =>
             claim.Type == DashboardAuthenticationDefaults.LdapGroupClaimType
             && claim.Value.Contains("GwAdmin", StringComparison.OrdinalIgnoreCase));
+
+        // IntegrationTests-023: DashboardAuthenticator.CreatePrincipal emits a
+        // ClaimTypes.Role claim derived from MapGroupsToRoles. The seeded
+        // GroupToRole map (GwAdmin -> Admin) means the admin principal must
+        // carry Role=Admin alongside the raw LDAP-group claim. A regression in
+        // MapGroupsToRoles (returning an empty list, missing the RDN fallback)
+        // would silently pass without this assertion.
+        Assert.Contains(result.Principal.Claims, claim =>
+            claim.Type == ClaimTypes.Role
+            && claim.Value == DashboardRoles.Admin);
     }
 
     [LiveLdapFact]