currentScenario()/currentRole() read the URL param before sessionStorage, so a
stale ?scenario=/?role= in the address bar overrode the switcher on reload
("stuck on slow"). The switcher now strips both dev params from the URL
(pure stripDevParams + history.replaceState) before reloading, so the stored
value wins.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
