processedCommands and recentResults Sets grew infinitely because
Date.now() in dedup keys made deduplication impossible and no
session.deleted cleanup existed.
- Extract ProcessedCommandStore with maxSize cap and TTL-based eviction
- Add session cleanup on session.deleted event
- Remove Date.now() from dedup keys for effective deduplication
- Add dispose() for interval cleanup
Tests: 3 pass, 9 expects
YeonGyu-Kim