d0ac6c435f
The reliability layer over the durable inbox (Stage 2, 2bc5f3a): push a nudge
into the primary's own herdr pane the moment a no-waiter reply lands, remind on
a bounded backoff until the primary drains (ack=drain), degrade to pull when the
primary pane isn't resolvable. Grounds the seam: the primary terminal_id is
already derivable via ConnectionIdentity/PaneLocator, just discarded today.
Refs gitea #5.