v1.3.0

Added

• The dispatcher stops claiming for a stream whose broker is unreachable. Finding a broker gone
  used to change nothing about the loop: it kept claiming a batch, failing to publish it and writing
  the failure back for the whole outage.

  What that cost was not the retries. A deferred message is rescheduled a backoff into the future,
  so retrying an outage is self-limiting. New messages are not — every insert arriving while the
  broker is down wakes the pipeline through LISTEN/NOTIFY and was claimed, attempted and written
  back at once. The load removed is proportional to how busy the producer is rather than to how long
  the outage lasts.

  The pause starts at one poll interval and doubles up to OUTBOX_DISPATCH_PAUSE_MAX (30s), and
  one ordinary claim is let through each time it elapses. The trial is a real batch rather than a
  health check on purpose: publishing is the capability that matters, and a health check is only a
  proxy for it — one that can be green while the exchange the messages need is not there. A wake-up
  is not allowed past the pause, since it carries no information the breaker does not already have.

  The ceiling matches the delay the RabbitMQ supervisor backs off to between reconnection attempts,
  so pausing adds nothing to how soon a returning broker is noticed. 0 restores the previous
  behaviour, which is also how the tests prove the pause is what makes the difference.

• outbox_stream_paused{stream}, 1 while a stream has stopped claiming. This is not
  decoration: while claims are held back nothing is published, so outbox_messages_deferred_total
  stops advancing precisely when an outage is most established. The gauge is the signal that
  outlives the condition it reports.

Changed

• The shipped OutboxBrokerUnreachable alert now joins outbox_stream_paused with the deferral
  rate. On the rate alone it would have cleared itself a minute into every outage it exists to
  report.
• Pipeline.RunOnce returns a dispatch.Result — claimed, delivered and deferred — instead of a
  bare count, so the run loop can tell an outage from a batch that simply failed.