fix tester-reported bugs

desktop/src/main/java/org/example/petshopdesktop/api/ChatRealtimeClient.java

@@ -84,6 +84,7 @@ public class ChatRealtimeClient implements WebSocket.Listener {
     public void initializeState(List<ConversationResponse> conversations) {
         synchronized (lock) {
             globalConversations.clear();
+            readConversationIds.clear();
             for (ConversationResponse conv : conversations) {
                 globalConversations.put(conv.getId(), conv);
             }

desktop/src/test/java/org/example/petshopdesktop/ValidatorTest.java

@@ -183,7 +183,7 @@ class ValidatorTest {
     //isValidPhoneNumber
     @Test
     void isValidPhoneNumber_validFormat_returnsEmpty() {
-        assertTrue(Validator.isValidPhoneNumber("403-555-1234", "Phone").isEmpty());
+        assertTrue(Validator.isValidPhoneNumber("(403) 555-1234", "Phone").isEmpty());
     }
 
     @Test