Atproto, types overhaul and error handling

Breaks off from Atrium-rs's types because they are implemented
inconsistently, which makes them harder to use. Additionally, I wanted
sqlx support so I decided I'd need to reimplement them to some extent
anyways.

This was done with reference to the atproto documentation but
specifically not the atrium-rs codebase so I wouldn't have to think
about licenses.

This adds the types and error module in atproto. It also touches
Cargo.toml for some new dependencies and some shared dependencies. It
required thiserror, so I looped that into the workspace meaning that
this commit touches db.

some things to keep in mind:
- There is no CID parsing
- None of this is tested, nor are there any tests written. We're playing
  fast and loose baby~

Cargo.toml

@@ -7,6 +7,7 @@ async-trait = "0.1.88"
 atproto = { path = "./atproto" }
 serde = "1.0.219"
 serde_json = "1.0.140"
+thiserror = "2.0.12"
 tokio = { version = "1.45.0", features = ["macros", "rt-multi-thread"] }
 tracing = "0.1.41"
 tracing-subscriber = "0.3.19"