feat(07-01): install DKV deps, add Prisma models, wire ScheduleModule + crypto export

- pnpm add imapflow@^1.4.3, pdf-parse@^2.4.5, xlsx@^0.18.5 to @tessera/api
- Append DkvModuleConfig, DkvVehicleMaster, DkvInvoiceHistory, SmtpConfig models to schema.prisma (15 models total)
- Add ScheduleModule.forRoot() to AppModule imports (prerequisite for DkvSchedulerService)
- Export CalendarCryptoService from CalendarModule (needed by DkvModule + SettingsModule)
- Create apps/api/src/dkv/dkv.types.ts with DkvVehicleBlock, DkvTransaction, InboxConfig, InboxEmail, InboxAttachment, ExportRow interfaces

apps/api/prisma/schema.prisma

@@ -168,3 +168,66 @@ model CalendarSource {
   @@index([userId])
   @@index([tenantId])
 }
+
+model DkvModuleConfig {
+  id                  String   @id @default(uuid())
+  tenantId            String   @unique
+  protocol            String   @default("imap")        // 'imap' | 'exchange'
+  host                String?
+  port                Int?
+  encryption          String   @default("ssl-tls")     // 'none' | 'starttls' | 'ssl-tls'
+  folder              String   @default("INBOX")
+  senderFilter        String?
+  pollIntervalMin     Int      @default(60)
+  isActive            Boolean  @default(false)
+  exportRecipient     String?
+  vehicleFormatString String   @default("{Marke}/{Modell}/{Kennzeichen}")
+  encryptedInboxCreds String?  // AES-256-GCM: JSON { username, password } encrypted
+  createdAt           DateTime @default(now())
+  updatedAt           DateTime @updatedAt
+
+  @@index([tenantId])
+}
+
+model DkvVehicleMaster {
+  id          String   @id @default(uuid())
+  tenantId    String
+  kennzeichen String
+  marke       String
+  modell      String
+  fahrer      String   // "Vorname Nachname"
+  createdAt   DateTime @default(now())
+  updatedAt   DateTime @updatedAt
+
+  @@unique([tenantId, kennzeichen])
+  @@index([tenantId])
+}
+
+model DkvInvoiceHistory {
+  id                  String   @id @default(uuid())
+  tenantId            String
+  datumZeit           DateTime @default(now())
+  rechnungsnummer     String
+  anzahlFahrzeuge     Int      @default(0)
+  anzahlTransaktionen Int      @default(0)
+  status              String   // 'Verarbeitet' | 'Fehler' | 'Versand fehlgeschlagen'
+  errorMessage        String?
+  exportFilename      String?
+  createdAt           DateTime @default(now())
+
+  @@index([tenantId])
+  @@index([datumZeit])
+}
+
+model SmtpConfig {
+  id                String   @id @default(uuid())
+  tenantId          String   @unique
+  host              String
+  port              Int      @default(587)
+  encryption        String   @default("starttls")  // 'none' | 'starttls' | 'ssl-tls'
+  username          String?
+  encryptedPassword String?  // AES-256-GCM via CalendarCryptoService
+  fromAddress       String
+  createdAt         DateTime @default(now())
+  updatedAt         DateTime @updatedAt
+}