Add form field preservation in gifting flow

- Preserve description, amount, and unit code when navigating between gifting steps
- Add form field props to EntitySelectionStep and GiftedDialog components
- Update ContactGiftingView to handle form state persistence in URL parameters

src/components/GiftedDialog.vue

@@ -18,6 +18,9 @@
         :to-project-id="toProjectId"
         :giver="giver"
         :receiver="receiver"
+        :description="description"
+        :amount-input="amountInput"
+        :unit-code="unitCode"
         :notify="$notify"
         @entity-selected="handleEntitySelected"
         @cancel="cancel"