Magic Advent Calendar 1.0.6 – translation audit

Updated de_DE and de_AT PO/MO, generated POT.
Includes PHP gettext calls used by wp_localize_script (frontend quiz).

Code observations (not changed):
- includes/frontend/class-frontend.php has duplicate localization keys `next`, `finish`, `answerRequired`; later values overwrite earlier ones.
- JavaScript literals not passed through PHP gettext/localization remain untranslated. Review any user-facing JS literals separately.
- Existing translations were preserved where possible.
