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

docs/requirements/Component-ManagementService.md

@@ -194,7 +194,7 @@ The two-person authorization workflow for writes through the MxAccess Gateway. B
 - **ListApiKeys** / **CreateApiKey** / **UpdateApiKey** / **EnableApiKey** / **DisableApiKey** / **DeleteApiKey**: Manage API keys.
 - **ListRoleMappings** / **CreateRoleMapping** / **UpdateRoleMapping** / **DeleteRoleMapping**: Manage LDAP group-to-role mappings.
 - **ListScopeRules** / **AddScopeRule** / **DeleteScopeRule**: Manage site scope rules on role mappings.
-- Every role-mapping and scope-rule mutation (Create/Update/DeleteRoleMapping, Add/DeleteScopeRule) calls `RoleMappingCache.Invalidate()` as a **post-commit** action, so the change takes effect for the next role mapping on the node that served the command instead of after the `RoleMappingCacheSeconds` TTL (default 30 s); the other central node still converges within that TTL. Post-commit, because invalidating inside the transaction would let a concurrent mapping re-cache the pre-change table.
+- Every role-mapping and scope-rule mutation (Create/Update/DeleteRoleMapping, Add/DeleteScopeRule) calls `RoleMappingCache.Invalidate()` as a **post-commit** action, so the change takes effect for the next role mapping on the node that served the command instead of after the `RoleMappingCacheSeconds` TTL (default 30 s), and publishes `RoleMappingsInvalidated` on the central cache-invalidation topic so the other central node drops its snapshot too (audit D1, ScadaBridge#100 item 3); the TTL is only the fallback if that best-effort broadcast is lost. The external-definition edit handlers do the same with `ExternalDefinitionsInvalidated` (#65, #83). Post-commit, because invalidating inside the transaction would let a concurrent mapping re-cache the pre-change table.
 
 ### Audit Log