Add escalation summary generation and product search rejection

Add production features: circuit breaker, exponential backoff, semantic caching, intent-based scope handling

Complete state mutation refactor: all nodes now return partial dicts (LangGraph reducer pattern)

Fix critical bugs: compensation for late orders, escalation detection, conversation history improvements

Add clarification node for missing order IDs + rule-based fallbacks to prevent 504 timeout

Initial commit: Olist intelligence layer with database