snooze vor expired, contracts, display snoozed contracts if an item is missing, un snooze implemented, fixed invoice upload bug

backend/prisma/migrations/20260208081918_add_next_review_date/migration.sql

@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE `Contract` ADD COLUMN `nextReviewDate` DATETIME(3) NULL;

backend/prisma/schema.prisma

@@ -545,6 +545,9 @@ model Contract {
   stressfreiEmailId       Int?
   stressfreiEmail         StressfreiEmail? @relation(fields: [stressfreiEmailId], references: [id])
 
+  // Snooze: Vertrag zurückstellen bis Datum (für Cockpit)
+  nextReviewDate          DateTime?       // Erneute Prüfung am
+
   notes                   String?         @db.Text
 
   energyDetails           EnergyContractDetails?