Refactor/hybrid encryption

[chadsec1]

This pull request adds an additional cryptographic primitive (McEliece8192128) in addition to ML-KEM-1024.
The reason I've picked McEliece8192128 specifically, is because it's based on a different problem that lattice-based KEMs, meaning an adversary would need to break both problems in order to retrieve the one-time-pad pad(s).

I've avoided adding support for Curve448 or other classical algorithms, to keep code complexity low, and avoid near future headaches when quantum computers become strong enough to delete it and we'd have to update it. (our software will never include auto-updates, and we plan to make it federated).

Additionally, I've reworked the perfect-forward-secrecy. In previous updated, we only rotated ML-KEM-1024 keys on every 2 OTP pad batches sent, this update makes it rotate on every batch. I've also fixed some important logic issues that affected earlier versions of Coldwire.

I've also simplified some parts of the logic, reducing the attack surface overall.

And last but not least, I've added fully async perfect-forward-secrecy and messaging support. Neither contacts need to be online once a KEM key rotation occurs.