Fix stale `AGGREGATE` label (actual enum: `COUNT_IN_WINDOW`). Expand EXCHANGE_MATCH section with both fire modes, PER_EXCHANGE config-surface restrictions (0 for reNotifyMinutes/forDurationSeconds, at-least-one-sink rule), exactly-once guarantee scope, and the first-run backlog-cap knob. Surface the new config in application.yml with the 24h default and the opt-out-to-0 semantics. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>