Persist user carts in database

src/schema.graphql

@@ -191,6 +191,28 @@ type Product {
   availableInWarehouses: [ProductWarehouseBalance!]!
 }
 
+type CartItem {
+  id: ID!
+  productId: ID!
+  productName: String!
+  sku: String!
+  isCustomizable: Boolean!
+  quantity: Float!
+  parameters: JSON!
+  createdAt: DateTime!
+  updatedAt: DateTime!
+}
+
+type Cart {
+  id: ID!
+  userId: ID!
+  deliveryAddressId: ID
+  deliveryAddress: DeliveryAddress
+  items: [CartItem!]!
+  createdAt: DateTime!
+  updatedAt: DateTime!
+}
+
 type OrderItem {
   id: ID!
   productId: ID
@@ -266,6 +288,7 @@ type Query {
   healthcheck: String!
   me: User
   myCounterpartyProfile: CounterpartyProfile
+  myCart: Cart!
   myDeliveryAddresses: [DeliveryAddress!]!
   myMessengerConnections: [MessengerConnection!]!
   myNotificationHistory(channel: MessengerType!, limit: Int = 50): [NotificationHistoryItem!]!
@@ -340,6 +363,11 @@ input CreateMyDeliveryAddressInput {
   fiasId: String
 }
 
+input UpdateCartItemQuantityInput {
+  productId: ID!
+  quantity: Float!
+}
+
 input ReadyOrderItemInput {
   productId: ID!
   quantity: Float!
@@ -400,6 +428,11 @@ type Mutation {
   acceptInvitation(input: AcceptInvitationInput!): User!
   connectMessenger(input: ConnectMessengerInput!): MessengerConnection!
   upsertMyCounterpartyProfile(input: UpsertMyCounterpartyProfileInput!): CounterpartyProfile!
+  addProductToCart(productId: ID!): Cart!
+  updateCartItemQuantity(input: UpdateCartItemQuantityInput!): Cart!
+  removeCartItem(productId: ID!): Cart!
+  setCartDeliveryAddress(addressId: ID): Cart!
+  clearCart: Cart!
   createMyDeliveryAddress(input: CreateMyDeliveryAddressInput!): DeliveryAddress!
   setMyDefaultDeliveryAddress(addressId: ID!): DeliveryAddress!
   deleteMyDeliveryAddress(addressId: ID!): Boolean!