Expose Prometheus-style metrics endpoint and add counters for send requests, idempotency replays, and cursor pagination calls, including a safe in-process fallback exposition when prometheus_client is unavailable.
Made-with: Cursor
Add BFF runtime support for chat idempotency (header priority over body) with bounded in-memory TTL/LRU replay cache, implement cursor-based pagination for chats and messages, and add a safe NODA2 local router fallback for legacy runs without NODE_ID.
Made-with: Cursor
