feat(flashcards): révision SM-2, génération IA et page /revision

Livre US-FLASHCARDS avec decks, session de révision, stats et migration Prisma. Finalise le Web Clipper (i18n 15 langues) et corrige les erreurs ESLint bloquant la CI.

Co-authored-by: Cursor <cursoragent@cursor.com>

memento-note/locales/en.json

@@ -2404,6 +2404,64 @@
       "Japonais": "Japanese"
     }
   },
+  "flashcards": {
+    "generateTitle": "Generate flashcards",
+    "generateAction": "Generate with AI",
+    "confirmSave": "Save to deck",
+    "generateFailed": "Could not generate flashcards",
+    "saveFailed": "Could not save flashcards",
+    "savedCount": "{count} flashcards saved",
+    "cardCount": "Number of cards",
+    "styleLabel": "Card style",
+    "style": {
+      "qa": "Q&A",
+      "cloze": "Cloze",
+      "concept": "Concept"
+    },
+    "previewHint": "Edit cards before saving",
+    "frontPlaceholder": "Question / front",
+    "backPlaceholder": "Answer / back",
+    "toolbarGenerate": "Generate flashcards",
+    "tabDecks": "Decks",
+    "tabProgress": "Progress",
+    "emptyDecks": "No flashcard decks yet",
+    "emptyDecksHint": "Open a note and use the graduation cap in the toolbar to generate cards with AI.",
+    "createDeck": "Create deck",
+    "newDeckPlaceholder": "Thematic deck name…",
+    "deckCreated": "Deck created",
+    "dueCount": "{count} due today",
+    "upToDate": "Up to date",
+    "cardCountLabel": "{count} cards",
+    "masteredShort": "mastered",
+    "viewDeck": "Details",
+    "review": "Review",
+    "startReview": "Start review",
+    "activeDeck": "Active deck",
+    "statTotal": "Total: {count}",
+    "statDue": "Due: {count}",
+    "statMastered": "Mastered: {count}",
+    "exitSession": "Exit session",
+    "previous": "Previous",
+    "next": "Next",
+    "front": "Front",
+    "back": "Back",
+    "tapToFlip": "Space or tap to flip",
+    "grade": {
+      "hard": "Hard (1)",
+      "difficult": "Difficult (2)",
+      "good": "Good (3)",
+      "easy": "Easy (4)"
+    },
+    "sessionComplete": "Session complete",
+    "backToDecks": "Back to decks",
+    "loadDeckFailed": "Could not load deck",
+    "reviewFailed": "Could not save review",
+    "heatmapTitle": "Review activity",
+    "heatmapLast90": "Last 90 days",
+    "retentionRate": "Retention rate",
+    "retentionCurve": "Weekly retention",
+    "difficultCards": "Hardest cards"
+  },
   "brainstorm": {
     "title": "Waves of Thought",
     "subtitle": "Unfold dimensions of potentiality",