Create a streaming-compatible variant of the Kratos validation middleware. This is already available as a draft that should probably just be reviewed/merged: https://github.com/project-kessel/relations-api/pull/116 - it was originally marked as a draft because there's more to do, but merging it as-is should be an improvement, just an incomplete one.

Note: this is more technical debt than metrics/tracing/alerting but a very similar process to the other streaming variants.