//TODO
- background job for re-delivery
- POST::/messages
- https://firebase.google.com/docs/cloud-messaging/send-message#rest
- List subscriptions on all owned channels (RESTful?)
- deploy
- full-text-search: https://www.sqlite.org/fts5.html#contentless_tables
- route to re-create keys
- ack/read deliveries && return ack-count
- compat methods should bind body as form-data