The in-session progress bar reads session.cardsShown/cardsCorrect/cardsIncorrect,
but the session store's answer() never refreshed the session object — the backend
tracked the counters but the client kept the stale start values (all 0), so the bar
appeared frozen. answer() now mirrors the backend's increment locally; end() still
replaces with authoritative server totals. Adds an E2E regression test.
Add e2e/ux.spec.ts covering the ⌘K search palette, lesson detail page,
stats sections, and the legacy /admin → /lessons redirect.
Also fixes two issues uncovered by running the full suite:
- Skip auth rate limiter in e2e by running the backend with NODE_ENV=test
(registration limit of 5 was tripping later tests).
- Render the card table for lesson owners even when the lesson has zero
cards, so the first card can be added from the detail page.
