This avoids a case where a very large import would overflow the
"celery" queue with reindex tasks that would block the inbound
processing tasks. Now we have good priorization.
We are going to release a 0.1 version soon, along with our first production deployment. Starting from there, migrations and a consistent developer experience will be officially supported. To make that easier, this large patch cleans up several areas:
* Reset migrations one last time
* Update models for storage efficiency (move textchoices to integerchoices on high-volume tables)
* Use Blobs for mail mime data and draft bodies. Having them in a separate PG table is a first step, we will later start offloading them to object storage.
* Add default ZSTD compression to blobs
* Add per-domain DKIM Keys
* Add DNS check and provisioning, with a first Scaleway provider
* Fix Keycloak user provisioning
* Fix Attachment storage, they are now stored individually only at the drafting stage. Afterwards they are extracted from the main blob. This may be optimized later but at least we only store once. For JMAP compatibility, this requires using fake IDs in the blob API route.
* Add a management command and recurring task to retry unsent messages
* Improve the local developer experience with new ports and make commands
* Repackage MTA-in and MTA-out to be closer to Backend: Poetry, multi-step Dockerfile, move compose and makefile to the root
* Migrate to OpenSearch
* Improve overall documentation and add a self-hosting page
Contributes to #177 and #185
