Playwright spec for /zeitstrahl: the primary journey (hide Letters → letter
cards vanish + trigger reports "1 aktiv" → reset restores) and a 375px axe pass
with the collapsible open in light and dark mode. Not skipped — #779 ships the
route. E2E is not wired into CI, so this runs locally only for now.
Refs #780
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
