feat: Implement persistent chat clearing functionality by adding a new service method and integrating it into the useMessaging hook.

src/hooks/useMessaging.ts

@@ -346,9 +346,30 @@ export function useMessaging(options: UseMessagingOptions = {}): UseMessagingRet
     []
   );
 
-  // Clear messages from current conversation view (local only)
-  const clearMessages = useCallback(() => {
-    setMessages([]);
+  // Clear messages from current conversation (persisted to backend)
+  const clearMessages = useCallback(async () => {
+    const convId = currentConversationIdRef.current;
+    if (!convId) return;
+
+    try {
+      await messagesService.clearChat(convId);
+      setMessages([]);
+      // Update conversation preview in the list
+      setConversations((prev) =>
+        prev.map((c) =>
+          c.id === convId
+            ? { ...c, lastMessageText: null, lastMessageAt: null, unreadCount: 0, userUnreadCount: 0, agentUnreadCount: 0 }
+            : c
+        )
+      );
+      setCurrentConversation((prev) =>
+        prev && prev.id === convId
+          ? { ...prev, lastMessageText: null, lastMessageAt: null, unreadCount: 0, userUnreadCount: 0, agentUnreadCount: 0 }
+          : prev
+      );
+    } catch (err) {
+      console.error('Failed to clear chat:', err);
+    }
   }, []);
 
   // Update user online status (called from status change events)