feat(central): one central cache-invalidation topic; role-mapping and external-definition caches follow peer edits (ScadaBridge#100 item 3, ScadaBridge#83)

The #96 site-psk-invalidation topic was the first cross-node invalidation broadcast.
It is generalised into ONE central DistributedPubSub topic, central-cache-invalidation,
carrying typed messages (Commons ICentralCacheInvalidation: SitePskInvalidated,
RoleMappingsInvalidated, ExternalDefinitionsInvalidated, InboundApiMethodInvalidated)
in an envelope stamped with the publisher's process-unique origin id.

- Host: CentralCacheInvalidationBus (ICentralCacheInvalidationPublisher, no-op until
  the mediator is set, never throws) and CentralCacheInvalidationSubscriber, which
  skips its own node's envelopes and hands the peer's to every registered
  ICentralCacheInvalidationHandler (a failing handler does not stop the rest).
  Replaces SitePskInvalidationSubscriber.
- Migration of #96: SitePskRotationInvalidator publishes through the bus and is the
  PSK handler; SitePskInvalidated keeps its type name and is also published bare on
  site-psk-invalidation, which the subscriber still listens to, so a mixed-version
  central pair keeps exchanging PSK invalidations. Remove after one release.
- Audit D1: RoleMappingCache is a handler; ManagementActor's post-commit role-mapping
  invalidation also publishes RoleMappingsInvalidated, so a revocation is immediate on
  the peer instead of after RoleMappingCacheSeconds.
- Audit D3 / #83 (peer half): ExternalDefinitionLookupCache is a handler; the 9
  ManagementActor handlers and the Transport bundle importer publish
  ExternalDefinitionsInvalidated after commit. (#83's local import half was already in.)

TTLs remain the fallback for a lost broadcast or a direct SQL edit. Tests: bus and
subscriber unit tests (origin filter, legacy topic), peer-node tests through the real
caches in ManagementService.Tests, importer publish, composition root, and a real
two-node cluster from the production HOCON (CentralCacheInvalidationTwoNodeTests)
proving every message type crosses with the production serializer. Docs: Host,
Communication, Security, ManagementService, ESG, and the #85 cache audit.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

tests/ZB.MOM.WW.ScadaBridge.ManagementService.Tests/RoleMappingCacheInvalidationTests.cs

@@ -6,6 +6,7 @@ using NSubstitute;
 using ZB.MOM.WW.ScadaBridge.Commons.Entities.Security;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Services;
+using ZB.MOM.WW.ScadaBridge.Commons.Messages.Communication;
 using ZB.MOM.WW.ScadaBridge.Commons.Messages.Management;
 using ZB.MOM.WW.ScadaBridge.Security;
 
@@ -20,6 +21,9 @@ public class RoleMappingCacheInvalidationTests : TestKit
 {
     private readonly ISecurityRepository _repo = Substitute.For<ISecurityRepository>();
     private readonly RoleMappingCache _cache = new(TimeProvider.System);
+    // The other central node's cache, reached only through the peer invalidation (audit D1).
+    private readonly RoleMappingCache _peerCache = new(TimeProvider.System);
+    private readonly PeerCacheInvalidationPublisher _publisher;
     private readonly ServiceCollection _services = new ServiceCollection().AddTestConfigurationTransaction();
     private List<LdapGroupMapping> _mappings = [new("Ops", "Deployer") { Id = 5 }];
 
@@ -33,6 +37,8 @@ public class RoleMappingCacheInvalidationTests : TestKit
         _services.AddScoped(_ => _repo);
         _services.AddScoped(_ => Substitute.For<IAuditService>());
         _services.AddSingleton(_cache);
+        _publisher = new PeerCacheInvalidationPublisher(_peerCache);
+        _services.AddSingleton<ICentralCacheInvalidationPublisher>(_publisher);
     }
 
     private IActorRef CreateActor() =>
@@ -84,4 +90,45 @@ public class RoleMappingCacheInvalidationTests : TestKit
             await _repo.Received(1).GetAllMappingsAsync(Arg.Any<CancellationToken>()); // re-read, not served stale
         }
     }
+
+    /// <summary>
+    /// Audit D1 (ScadaBridge#100 item 3): a revocation made through this node reaches the peer
+    /// central node's snapshot at once, instead of after <c>RoleMappingCacheSeconds</c>.
+    /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    [Fact]
+    public async Task DeleteRoleMapping_IsVisibleOnThePeerNode()
+    {
+        var peerMapper = new RoleMapper(_repo, _peerCache);
+        Assert.Contains("Deployer", (await peerMapper.MapGroupsToRolesAsync(["Ops"])).Roles); // primes the peer
+
+        _mappings = [];
+        CreateActor().Tell(Admin(new DeleteRoleMappingCommand(5)));
+        ExpectMsg<ManagementSuccess>(TimeSpan.FromSeconds(5));
+
+        Assert.Empty((await peerMapper.MapGroupsToRolesAsync(["Ops"])).Roles);
+    }
+
+    /// <summary>Every mapping / scope-rule mutation tells the peer, once, after commit.</summary>
+    [Fact]
+    public void EveryMappingMutation_TellsThePeer()
+    {
+        object[] commands =
+        [
+            new CreateRoleMappingCommand("Eng", "Designer"),
+            new UpdateRoleMappingCommand(5, "Ops", "Viewer"),
+            new DeleteRoleMappingCommand(5),
+            new AddScopeRuleCommand(5, 2),
+            new DeleteScopeRuleCommand(9),
+        ];
+        var actor = CreateActor();
+        foreach (var command in commands)
+        {
+            actor.Tell(Admin(command));
+            ExpectMsg<ManagementSuccess>(TimeSpan.FromSeconds(5));
+        }
+
+        Assert.Equal(commands.Length, _publisher.Published.Count);
+        Assert.All(_publisher.Published, i => Assert.IsType<RoleMappingsInvalidated>(i));
+    }
 }