Two beheer specs log in as bram-beheerder back to back, so both submit the
code for the same 30-second counter. Keycloak's otpPolicyCodeReusable
defaults to false, so it refuses the second one as invalid credentials and
the beheer portal never loads — which is how verify-e2e went red on #158.
Pins the counter choice as a pure function of "now" and the last counter
this medewerker spent, so the guard is checkable without a browser.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
