feat: add bounded npc memory retention

docs/ACTION_SYSTEM_ARCHITECTURE.md

@@ -76,7 +76,9 @@ events into `RelationshipSystem`. When an NPC arrives beside a worker at the
 same non-storage activity site, the manager may transfer one direct known fact
 and applies its consequence only to that newly informed listener. It exposes
 knowledge, provenance, relationship, and cause queries without moving social
-authority into UI.
+authority into UI. After consequences are known, it protects current causal
+facts, enforces the recent-memory cap, and runs age review from authoritative
+simulation ticks.
 
 ### VillageEconomy
 
@@ -101,6 +103,10 @@ authority into UI.
   legacy, with a stable source NPC ID for direct communication;
 - permits one performed/witnessed fact to cross one co-located social hop, but
   does not relay communicated or ambiguous legacy facts;
+- orders communication by lasting relationship relevance, then acquisition
+  recency;
+- retains current relationship causes and at most three other recent facts per
+  NPC, expiring day-old recent facts at deterministic review boundaries;
 - captures evidence only when the event happens, never from current positions
   during restore;
 - answers deterministic known-event and knower queries without formatting