Implements ticket #239 for Sprint 3:
- ObservationTrigger enum: RoutineDeviation (NPC not at expected
routine location), Absence (expected location visible but NPC
missing), NewEntity (unknown entity in LOS)
- ObservationEventQueue resource with push/drain/len/is_empty
- generate_observation_events system runs after emit_observation_events
but before process_knowledge_events so it can compare current
snapshot against previous-tick knowledge state
- Populate PerceptionPlugin with ObservationEventQueue resource and
system registration with correct ordering constraints
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
jpmschweitzerandClaude Opus 4.6
9c3c32e854