chore: move crates into crates/ dir (#1958)

I'd like to tidy up the root a little, and it's nice to have all the
rust crates in one place

crates/atuin-server-postgres/migrations/20231202170508_create-store.sql

@@ -0,0 +1,15 @@
+-- Add migration script here
+create table store (
+	id uuid primary key,            -- remember to use uuidv7 for happy indices <3
+  client_id uuid not null,        -- I am too uncomfortable with the idea of a client-generated primary key, even though it's fine mathematically
+	host uuid not null,             -- a unique identifier for the host
+	idx bigint not null,       -- the index of the record in this store, identified by (host, tag)
+	timestamp bigint not null,      -- not a timestamp type, as those do not have nanosecond precision
+	version text not null,
+	tag text not null,              -- what is this? history, kv, whatever. Remember clients get a log per tag per host
+	data text not null,            -- store the actual history data, encrypted. I don't wanna know!
+	cek text not null,            
+
+	user_id bigint not null,        -- allow multiple users
+	created_at timestamp not null default current_timestamp
+);