feat: implement user reporting functionality with a dedicated modal and service, integrated into the chat header.

src/components/message/ChatHeader.tsx

@@ -16,6 +16,7 @@ interface ChatHeaderProps {
   typingText?: string;
   onClearChat?: () => void;
   onDeleteConversation?: () => void;
+  onReportUser?: () => void;
 }
 
 export function ChatHeader({
@@ -30,6 +31,7 @@ export function ChatHeader({
   typingText,
   onClearChat,
   onDeleteConversation,
+  onReportUser,
 }: ChatHeaderProps) {
   const [isMenuOpen, setIsMenuOpen] = useState(false);
   const [isMuted, setIsMuted] = useState(false);
@@ -49,9 +51,7 @@ export function ChatHeader({
     },
     {
       label: 'Report User',
-      onClick: () => {
-        // Placeholder — no backend endpoint yet
-      },
+      onClick: () => onReportUser?.(),
     },
     {
       label: 'Delete Conversation',