Updated sqlc setup for initial user creation.

sql/schema.sql

@@ -1,6 +1,7 @@
 CREATE TABLE users (
-  id   BIGSERIAL PRIMARY KEY,
-  name text      NOT NULL,
-  age  int       NOT NULL
+  id BIGSERIAL           PRIMARY KEY,
+  email TEXT             NOT NULL UNIQUE,
+  password TEXT          NOT NULL,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
 );