Revert detectAndEnqueueRebuildFromHeartbeat (Bridge 2) — master
should not drive rebuild assignments from heartbeat. The primary
owns data-control recovery per the V2 authority split.
Fix Bridge 1: NeedsRebuildObserved now carries per-replica identity.
resolveReplicaIDForShipper maps shipper DataAddr to ReplicaID via
the shipper group (works for RF=2 and RF=3+). The engine receives
the specific replica that needs rebuild, not a volume-level broadcast.
Primary-direct rebuild: the primary detects which replica needs
rebuild and will drive the session directly. The master learns about
it via subsequent heartbeat projection (needs_rebuild → rebuilding →
healthy). No master round-trip needed for the rebuild decision.
Added WALShipper.DataAddr() getter for address resolution.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
