fix: extract and send @mentions from chat messages

src/components/ChatPanel.tsx

@@ -146,9 +146,14 @@ export default function ChatPanel({ chatId, projectSlug }: Props) {
     setPendingFiles([]);
     setSending(true);
     try {
+      // Extract @mentions from text
+      const mentionMatches = text.match(/@(\w+)/g);
+      const mentions = mentionMatches ? [...new Set(mentionMatches.map(m => m.slice(1)))] : [];
+
       const msg = await sendMessage({
         chat_id: chatId,
         content: text,
+        mentions: mentions.length > 0 ? mentions : undefined,
         attachments: attachments.length > 0 ? attachments : undefined,
       });
       setMessages((prev) => {