feat: promote accepted proposals into matches

multiplayer-next.md

@@ -138,7 +138,9 @@ product policy are in [`docs/MATCHMAKING.md`](docs/MATCHMAKING.md).
 - [ ] **IN PROGRESS:** Fence proposals/participants in a PostgreSQL serializable transaction;
   prove loss of an acknowledged Redis write cannot split players. The Go store
   adapter now performs proposal insertion, participant insertion, and every
-  queue-ticket promotion in one rollback-safe SERIALIZABLE callback; the runnable
+  queue-ticket promotion in one rollback-safe SERIALIZABLE callback; accepted
+  proposals now atomically promote their exact team/slot map and tickets into an
+  `ALLOCATING` match; the runnable
   casual matcher can optionally use a Redis candidate projection and repairs an
   empty/lost index from PostgreSQL before claiming durably; live DB/Redis failover
   testing remains.