fix(marketplace): avoid inventory desync on failed offer insert

Expose whether a marketplace offer was persisted before mutating inventory state, refuse sells whose database insert failed, and synchronize the sold timestamp into the online seller's in-memory offer when present. This keeps failed or racing marketplace operations from desynchronizing credits/items.

Emulator/src/test/java/com/eu/habbo/habbohotel/catalog/marketplace/MarketPlaceOfferContractTest.java

@@ -0,0 +1,13 @@
+package com.eu.habbo.habbohotel.catalog.marketplace;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+class MarketPlaceOfferContractTest {
+
+    @Test
+    void exposesPersistenceState() {
+        assertDoesNotThrow(() -> MarketPlaceOffer.class.getDeclaredMethod("isPersisted"));
+    }
+}