The controller keeps the classifier's newest runs as one JSON array and
its settings as one JSON object, each under one KV key. A document this
build could not decode, as after a rollback past a build that added an
outcome or a settings field, failed every read and every write until
someone deleted the key by hand. A classifier newer than its controller
refused every run request for the missing `model`.
The run store now decodes the array one record at a time: a record that
does not decode is dropped with a WARN naming the bucket, key, index and
error, and a document that is not an array reads as no runs. Listing
keeps working, and the next recorded run writes back only the records
that decoded.
The stored settings ignore a field this build does not know; one that
still does not decode reads as the defaults with a WARN. The PUT body
keeps `deny_unknown_fields`. A PUT now always writes, so a PUT of the
defaults also replaces an undecodable document.
A run request without `model` runs on haiku, the swarm-wide setting's
default, now one constant in swarm-queue-client.
`schedules::read` gains a sibling, `read_with`, taking the decoder.
Closes#5162