- CardFace now renders one card surface that flips on Y-axis when
the user taps it. Both faces share a CSS-grid cell so the parent
height is the max of front/back, no jumpy reflow on flip.
- Tap-anywhere on the surface reveals (only while showBack is
false). The /learn page keeps the keyboard space/enter shortcut
via the existing handler; the standalone "Aufdecken" button is
now type-in-only (where the input field on the front breaks the
flip-mental-model).
- prefers-reduced-motion: reduce collapses the rotateY into an
instant cross-fade — same affordance, no vestibular trigger.
- Added a subtle "Tippe auf die Karte oder drücke Leertaste" hint
on the front face so the new affordance is discoverable.
- Fixed the last Phase-A leftover: focus:border-indigo-400 in the
type-in input → focus:border-app-accent.
39e508075a