Add three new ObserverSnapshot fields for client Sprint 18 tickets:
poi_list (Vec<PoiWire>) for minimap #151, examine_result
(Option<ExamineResultWire>) for #174, player_knowledge
(Option<PlayerKnowledgeWire>) for journal #264. POI list populated
live from KG-discovered PointOfInterest components. KG dump
serializes entity/fact knowledge with confidence, source, and state.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>