feat: add user role support to database and queries;

fix: add max length validation for refresh token in RefreshRequest;
refactor: use named constants for cache durations in AuthService;
refactor: select all user columns in GetValidUserByLoginCredentials query;

sqlc/query.sql

@@ -81,8 +81,7 @@ WHERE linfo.email = @email::text;
 
 ;-- name: GetValidUserByLoginCredentials :one
 SELECT
-  users.id,
-  users.username,
+  users.*,
   linfo.password_hash,
   linfo.totp_encrypted
 FROM users