The dashboard Update button's backend guard (#36263) already returns a
structured {ok:false, error:"docker_update_unsupported", message,
update_command} envelope (HTTP 200) when running in a Docker install,
instead of surfacing a raw SystemExit. But the frontend ignored that
envelope: runAction() only branched on a thrown error, so the 200 fell
through to the action-status poll, which reported a generic
"Action failed (exit 1)" toast and never showed the actual guidance.
Now runAction() inspects the update response and, on the
docker_update_unsupported case, surfaces the backend's guidance message
plus the recommended re-pull command directly (success-styled, since it's
actionable guidance — not a crash) without starting the poll.
Closes#34347.
4f7fe9bcff