update prisma/schema.prisma (add Invitation model)

prisma/schema.prisma

@@ -111,6 +111,13 @@ enum GuestCodeStatus {
   REVOKED
 }
 
+enum InvitationStatus {
+  PENDING
+  ACCEPTED
+  EXPIRED
+  REVOKED
+}
+
 // ----------------------------------------------------------------------------
 // USERS
 // ----------------------------------------------------------------------------
@@ -143,6 +150,7 @@ model User {
   handoverProtocols   HandoverProtocol[]
   guestCodesIssued    GuestCode[]
   notifications       Notification[]
+  invitationsSent     Invitation[]     @relation("InvitationsSent")
 
   @@map("users")
 }
@@ -168,10 +176,35 @@ model Room {
   tickets          Ticket[]
   inventoryItems   Inventory[]
   meterReadings    MeterReading[]
+  invitations      Invitation[]
 
   @@map("rooms")
 }
 
+// ----------------------------------------------------------------------------
+// INVITATIONS (Vermieter lädt Mieter per E-Mail ein)
+// ----------------------------------------------------------------------------
+
+model Invitation {
+  id          String           @id @default(uuid())
+  email       String
+  token       String           @unique
+  role        UserRole         @default(TENANT)
+  roomId      String?          @map("room_id")
+  room        Room?            @relation(fields: [roomId], references: [id])
+  invitedById String           @map("invited_by_id")
+  invitedBy   User             @relation("InvitationsSent", fields: [invitedById], references: [id])
+  status      InvitationStatus @default(PENDING)
+  expiresAt   DateTime         @map("expires_at")
+  acceptedAt  DateTime?        @map("accepted_at")
+
+  createdAt DateTime @default(now()) @map("created_at")
+
+  @@index([email])
+  @@index([status])
+  @@map("invitations")
+}
+
 // ----------------------------------------------------------------------------
 // CONTRACTS
 // ----------------------------------------------------------------------------