ADR-002: Durable Observer Delivery

Status: accepted
Decision: observer events are persisted to a delivery queue before Telegram send.

Rules

live same-session events and polling fallback events share the same delivery queue
queue delivery is retried with backoff
Telegram message routes are written only after successful delivery
foreign-thread approvals may degrade to waiting-state notifications when no actionable request_id exists
observer delivery now resolves against one global observer target at enqueue/send time
summary-panel updates, passive tool/output events, final answers, and on-demand full-log replies must remain distinguishable in queue payloads