users: migrations, queries, users crate: create user, get first admin user

crates/users/src/error.rs

@@ -0,0 +1,8 @@
+// error
+#[derive(thiserror::Error)]
+// the rest
+#[derive(Debug)]
+pub enum Error {
+    #[error("Database: {0}")]
+    Database(#[from] database::Error),
+}