feat(perception): add cognitive delay system for fog recognition (#423)

New CognitiveDelay component buffers perception events before emitting
KnowledgeEvents. Normal delay: 6 ticks (0.6s), urgent: 3 ticks (0.3s).
Drain system runs after emit_observation_events, before process_knowledge_events.

Adds pending_recognitions to ObserverSnapshot (protocol v7) for client
fog entity visualization. Includes cancellation when entity leaves LOS.

Monologue fires during delay (not after) per D-060 — cross-system
wiring deferred to follow-up ticket #451.

Ref: D-060 (cognitive delay), D-031 (10 tps), D-059 (fog layers)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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