Issue: https://github.com/BlowaterNostr/blowater/issues/102

Title: Operate a standalone encrypted binary storage service

Author: nostr:npub1dww6jgxykmkt7tqjqx985tg58dxlm7v83sa743578xa4j7zpe3hql6pdnf

Currently, images are encoded and encrypted as kind-4 events and big images are cut into chunks to bypass most relays' 100K or 256K event size limit.

This approach is bad for many reasons and it's better to operate a separate binary storage service that

1. accept encrypted data only

2. define a simple set of APIs so that

a. other clients can use it

b. other implementations can exist

3. figure out a payment solution

4. open source the implementation

a. other people can operate their own