add auth module

backend/internal/db/queries/query.sql

@@ -1,3 +1,11 @@
+-- name: CreateUser :one
+INSERT INTO users (username, password_hash)
+VALUES ($1, $2)
+RETURNING *;
+
+-- name: GetUserByUsername :one
+SELECT * FROM users WHERE username = $1;
+
 -- name: GetDeliveriesByDate :many
 SELECT * FROM deliveries WHERE date = $1;