[jmunar]

Summary

• Review tab in Challenges: problems you got wrong come back, per dataset and oldest first, once a cooling-off you pick on the page (Now, 1, 3 or 7 days; default 3) has passed since their last attempt.
• Two right answers in a row, each after its own wait, clear a mistake; a wrong answer resets the count, and right answers in practice count too.
• Replays are flagged (challenges_attempts.is_review) and never move the staircase, the graded draw's ability or the practice stats.
• Nothing about mistakes is stored: one CTE over the attempt history defines due, waiting and cleared. The migration adds is_review, challenges_review_current (the mistake being replayed) and challenges_settings (the cooling-off).
• Due-count badge on the Review tab, counting only visible datasets and swapped out of band after every answer or setting change. This is a small core change: an optional NavItem.badge plus layout::nav_badge and .nav-badge in core.css.
• Other entry points: a "Review mistakes (N)" link on picker cards, a mistakes line per dataset on Stats, and a review_mistakes command-bar action.
• Design doc in docs/ideas-05-challenges-replay-mistakes.md; requirements, architecture and the crate README are updated.
• Bumps ctutils 0.4.2 → 0.4.5 (RUSTSEC-2026-0385, published today) so cargo audit passes.

Test plan

• make check passes, with 30 new integration tests in crates/myapps-challenges/tests/challenges/review.rs. They cover:
  • each cooling-off value and the settings form, including a 400 for other values
  • clearing after two rights, and the reset after a wrong answer
  • practice answers counting toward clearing, and a cleared mistake reopening
  • Not now, stale forms and double taps, retired problems
  • the badge, including hidden datasets and the out-of-band swap
  • the picker link, the stats line, escaping, Spanish strings, plain-form redirects, and the CSS classes the markup relies on
  • the command bar action
• A unit test covers nav_badge, which is hidden at 0 and capped at 99+.
• A Playwright walkthrough at 390 px and 1280 px found no console errors, no failed requests and no XSS.
• New screenshot: docs/screenshots/challenges-review.png.
• Manual check: get a problem wrong in practice, set the cooling-off to Now on Review, replay it right twice, and watch the badge count down.

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