* Add key package table
* Key package upload endpoint
* Key package validation
* Parse and validate extensions
* Add MLS media type
* Improve MLS key package Swagger
* Compute and store key package refs
* Add endpoint for claiming key packages
* Add key package count endpoint
* Validate key package lifetimes
* Verify key package signatures
* Key package upload test
* Unit tests for key package validation functions
* Unit test KeyPackage extension parsing
* Fix key package integration test
* Add key package count test
* Test key package claim endpoint
* Validate key package protocol version
* Add nginz routes for MLS endpoints
* Upgrade nixpkgs
* Add crypto-cli to direnv
* Document key package lifetime option