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/prisma/schema.prisma

@@ -54,6 +54,7 @@ model User {
   noteClusters          NoteCluster[]
   bridgeNotes           BridgeNote[]
   bridgeSuggestions     BridgeSuggestion[]
+  flashcardDecks        FlashcardDeck[]
 }
 
 model Account {
@@ -111,6 +112,7 @@ model Notebook {
   children      Notebook[]     @relation("NotebookTree")
   user          User           @relation(fields: [userId], references: [id], onDelete: Cascade)
   workflows     Workflow[]
+  flashcardDeck FlashcardDeck?
 
   @@index([userId, order])
   @@index([userId])
@@ -195,6 +197,7 @@ model Note {
   bridgeNote                 BridgeNote?
   sourceLiveBlocks           LiveBlockRef[]           @relation("SourceLiveBlocks")
   targetLiveBlocks           LiveBlockRef[]           @relation("TargetLiveBlocks")
+  flashcards                 Flashcard[]
 
   @@index([isPinned])
   @@index([isArchived])
@@ -855,3 +858,49 @@ model BridgeSuggestion {
   @@index([userId, isDismissed])
   @@index([clusterAId, clusterBId])
 }
+
+model FlashcardDeck {
+  id         String      @id @default(cuid())
+  userId     String
+  notebookId String?     @unique
+  name       String
+  createdAt  DateTime    @default(now())
+  updatedAt  DateTime    @updatedAt
+  flashcards Flashcard[]
+  user       User        @relation(fields: [userId], references: [id], onDelete: Cascade)
+  notebook   Notebook?   @relation(fields: [notebookId], references: [id], onDelete: SetNull)
+
+  @@index([userId])
+}
+
+model Flashcard {
+  id             String            @id @default(cuid())
+  deckId         String
+  noteId         String?
+  front          String
+  back           String
+  type           String            @default("qa")
+  interval       Int               @default(1)
+  easinessFactor Float             @default(2.5)
+  nextReviewAt   DateTime          @default(now())
+  createdAt      DateTime          @default(now())
+  updatedAt      DateTime          @updatedAt
+  deck           FlashcardDeck     @relation(fields: [deckId], references: [id], onDelete: Cascade)
+  note           Note?             @relation(fields: [noteId], references: [id], onDelete: SetNull)
+  reviews        FlashcardReview[]
+
+  @@index([deckId])
+  @@index([noteId])
+  @@index([nextReviewAt])
+}
+
+model FlashcardReview {
+  id         String    @id @default(cuid())
+  cardId     String
+  grade      Int
+  reviewedAt DateTime  @default(now())
+  card       Flashcard @relation(fields: [cardId], references: [id], onDelete: Cascade)
+
+  @@index([cardId])
+  @@index([reviewedAt])
+}