A minimum viable atproto PDS for protocol experimentation purposes

It's designed to be a single-user instance (i.e. it only hosts a single repo). This is a hardcoded constraint right now but I might make multiple repos technically possible at some point.

• Creating a new DID and publishing it.
• Creating new records (making posts, liking, replying, following, etc.)
• Deleting records (post deletion, unlikes, unfollows, etc.)
• Attaching blobs (e.g. images)
• Editing records (e.g. editing bio).
• Federated firehose.
• AppView proxying for most bsky endpoints (still missing some)

• Updating records works but is subtly incorrect (e.g. it will leak blob references)
• swapCommit/swapRecord options for repo ops (they're silently ignored).
• Firehose cursoring.
• Handle firehose "too big" conditions.
• No Lexicon validation (the client is assumed to be well-behaved!)
• A lot of error/unhappy-path handling (and sometimes we signal errors in non-standard ways).
• JWT refresh tokens
• Various security considerations (e.g. password hashing)
• Many many many other things...

• Fix aforementioned non-working things
• Figure out how to garbage-collect MST blocks
• Don't hold full MST state in memory, load blocks from DB on-demand
• Put blobs larger than some threshold in the filesystem, not in sqlite
• Tests
• Docs

• Design and implement a protocol for client-signed commits (so the server can avoid holding signing keys, and enabling the use of user-local HSMs)

• A read-only web interface for external sharing of posts.

1. Copy config.py.example to config.py, and edit it.

2. Run python3 create_identity.py

3. Update config.py with the new DID value you just generated

4. Create an _atproto TXT DNS record that points your handle domain name to your DID (or alternatively use the HTTP method) (more info here).

5. Run pds.py, and make the web server publicly accessible somewhere (I'm using an nginx reverse proxy). You might want to create a systemd unit, or docker container, or something like that (I wouldn't know, I suck at devops/sysadmin).

6. Run request_crawl.py to inform the PDS that we exist. (Maybe I'll make this automatic at some point in the future).

7. Log in with a client (the official https://bsky.app works) and make a post, and the BGS should see it!