auth services, middleware, and other stuff

internal/migrate/migrations/1-init_db.sql

@@ -6,6 +6,7 @@ CREATE TABLE todo(
 
 CREATE TABLE users(
     id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
-    email VARCHAR NOT NULL,
-    hashed_password VARCHAR NOT NULL
+    email VARCHAR NOT NULL UNIQUE,
+    hashed_password bytea NOT NULL,
+    salt bytea NOT NULL
 );