feat: duplicate an accommodation booking into a new draft

addresses #869f6z44f

src/Service/AccommodationBookingService.php

@@ -576,6 +576,33 @@ class AccommodationBookingService
      * @throws ImplausibleBookingPriceException if the new house prices the stay implausibly high;
      *                                          the booking is left at its old house
      */
+    /**
+     * Copies a booking into a fresh Entwurf, so the office can build a variation of an offer
+     * instead of keying the whole thing in again. Everything the customer was quoted comes
+     * along verbatim — house, dates, pax, the board and additional service snapshots, the
+     * discounts and the stored price breakdown — while AccommodationBooking::__clone() resets
+     * the identity and the lifecycle.
+     *
+     * Allowed from any status, including Bestätigt and Absage: nothing on the original is
+     * touched, and "same group, next season" is exactly the case this exists for. The price is
+     * deliberately not recomputed, see __clone().
+     */
+    public function duplicate(AccommodationBooking $booking): AccommodationBooking
+    {
+        $copy = clone $booking;
+
+        // Marks the copy where the office looks for it — the list is sorted and scanned by
+        // group name, and two identical rows are otherwise impossible to tell apart.
+        if (null !== $copy->getGroupName()) {
+            $copy->setGroupName($copy->getGroupName().' (Kopie)');
+        }
+
+        $this->entityManager->persist($copy);
+        $this->entityManager->flush();
+
+        return $copy;
+    }
+
     public function changeAccommodation(AccommodationBooking $booking, Accommodation $accommodation): void
     {
         if (!$booking->isDraft() || $booking->getAccommodation() === $accommodation) {