fix(iam): persist revocations across site replay and recovery

Retain source-ordered tombstones and parent grant boundaries across both IAM backends, cache reloads, and deliberate identity recreation. Reconcile deletions through a versioned, bounded replication protocol with restart-aware acknowledgements.

Cover inherited group grants, STS retention, same-key service recreation, absolute expiration, and failures after the durable commit. Document coordinated upgrades and the remaining consistency boundaries.

Signed-off-by: Feng Ruohang <rh@vonng.com>

buildscripts/rebrand-guard/compat-baseline.json

@@ -829,6 +829,7 @@
     "/site-replication/peer/bucket-ops",
     "/site-replication/peer/edit",
     "/site-replication/peer/iam-item",
+    "/site-replication/peer/iam-revisions",
     "/site-replication/peer/idp-settings",
     "/site-replication/peer/join",
     "/site-replication/peer/remove",
@@ -877,6 +878,7 @@
     "/v2/metrics/cluster",
     "/v2/metrics/node",
     "/v2/metrics/resource",
+    "/v3/site-replication/peer/iam-revisions",
     "/var/vcap/bosh",
     "/verifybinary",
     "/version",