fix(auth): a member behind the register's clock says the password changed

When a member's clock ran more than its allowance behind the register's,
the session after a reset was refused as unavailable (the re-review's tenth
finding), after the register had already reset the account and ended every
session, and the app read it as "this instance has no password sign-in".
It now has a refusal of its own (passwordChanged): the app says the password
was changed and to sign in again with the new one.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

packages/halkyon_base_server/test/integration/register/member_test.dart

@@ -1159,7 +1159,7 @@ void main() {
               isA<PasswordRefusedException>().having(
                 (error) => error.reason,
                 'reason',
-                PasswordRefusal.unavailable,
+                PasswordRefusal.passwordChanged,
               ),
             ),
           );