Matches the mockup: the "Show Answer" button is replaced by an in-card
"Tap card to reveal answer" hint, and clicking anywhere on the card
reveals it (guarded the same way Space already was - only while at the
live card and not yet revealed).
Add real session-history navigation (Previous/Next/Shuffle), compact
side panels, and a segmented progress row to match the mockup layout.
Flashcards now opens straight into Study, with library management
moved into the Options menu ("Manage Flashcards") and Export hidden
from the UI (Import stays). Shuffle is backed by a real, due-before-new
randomized pick on the backend, not a decorative toggle.
hz