Two bugs found by simulation testing:
1. Suspect nodes could never recover after dissemination budget expired.
When probing a target, the Suspect state was not re-enqueued into the
dissemination queue (only Dead was). After budget exhaustion, the
Suspect node never received a piggyback telling it it was suspected,
so it could never refute via incarnation bump. Fix: re-enqueue both
Suspect and Dead state on outgoing probes.
2. Registry entries merged before membership changes in same piggyback.
When a message carried both a death notification and registry entries,
the entries were merged first, then immediately tombstoned. Fix: split
extract_registry_piggyback into unpack + deferred merge, processing
membership changes before merging registry entries.
Authored by Claude, lovingly guided by Zachery Aaron Shores-Chmielewski
1c07f02be2