feat: add manual bank card ledger

Store exact RUB balances, atomic transfers, linked refunds and versioned edits independently of T-Bank. Add migration, HTTP and durability verification.

prisma/schema.prisma

@@ -12,6 +12,9 @@ model User {
   id              String           @id
   email           String           @unique
   passwordHash    String
+  bankCards       BankCard[]
+  expenseCategories ExpenseCategory[]
+  bankCardOperations BankCardOperation[]
   sessions        Session[]
   tbankConnection TbankConnection?
   createdAt       DateTime         @default(now())
@@ -37,3 +40,60 @@ model Session {
 
   @@index([userId])
 }
+
+model BankCard {
+  id String @id
+  userId String
+  name String
+  bankName String?
+  lastFour String?
+  openingBalanceKopecks BigInt
+  openingDate String
+  version Int @default(1)
+  archivedAt DateTime?
+  createFingerprint String
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+  user User @relation(fields: [userId], references: [id], onDelete: Restrict)
+  operations BankCardOperation[] @relation("SourceCard")
+  incomingOperations BankCardOperation[] @relation("TargetCard")
+  @@index([userId])
+}
+model ExpenseCategory {
+  id String @id
+  userId String
+  name String
+  nameKey String
+  seedKey String?
+  version Int @default(1)
+  user User @relation(fields: [userId], references: [id], onDelete: Restrict)
+  operations BankCardOperation[]
+  @@unique([userId, nameKey])
+  @@unique([userId, seedKey])
+}
+model BankCardOperation {
+  id String @id
+  userId String
+  kind String
+  cardId String
+  targetCardId String?
+  categoryId String?
+  originalExpenseId String?
+  amountKopecks BigInt
+  date String
+  description String?
+  version Int @default(1)
+  deletedAt DateTime?
+  createFingerprint String
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+  user User @relation(fields: [userId], references: [id], onDelete: Restrict)
+  card BankCard @relation("SourceCard", fields: [cardId], references: [id], onDelete: Restrict)
+  targetCard BankCard? @relation("TargetCard", fields: [targetCardId], references: [id], onDelete: Restrict)
+  category ExpenseCategory? @relation(fields: [categoryId], references: [id], onDelete: Restrict)
+  originalExpense BankCardOperation? @relation("RefundExpense", fields: [originalExpenseId], references: [id], onDelete: Restrict, onUpdate: NoAction)
+  refunds BankCardOperation[] @relation("RefundExpense")
+  @@index([userId, cardId, date])
+  @@index([userId, targetCardId, date])
+  @@index([originalExpenseId])
+}