feat: add study modes to Memorize page

- Add 4 study modes: order-limited, order-infinite, random-limited, random-infinite
- Add mode selector buttons with icons
- Update progress display for infinite modes
- Add translations for all 8 locales

messages/it-IT.json

@@ -304,6 +304,11 @@
       "showAnswer": "Mostra risposta",
       "nextCard": "Prossima",
       "again": "Ancora",
+      "modeOrderLimited": "Ordine",
+      "modeOrderInfinite": "Ciclo",
+      "modeRandomLimited": "Casuale",
+      "modeRandomInfinite": "Casuale Ciclo",
+      "restart": "Ricomincia",
       "hard": "Difficile",
       "good": "Buono",
       "easy": "Facile",