feat(chat): expand empty input actions

src/app/chat/components/chat-send-button.tsx

@@ -17,15 +17,18 @@ import styles from "./chat-send-button.module.css";
 export interface ChatSendButtonProps {
   disabled: boolean;
   hasContent: boolean;
+  isExpanded?: boolean;
   onClick: () => void;
 }
 
 export function ChatSendButton({
   disabled,
   hasContent,
+  isExpanded = false,
   onClick,
 }: ChatSendButtonProps) {
   const Icon = hasContent ? ArrowUp : Plus;
+  const ariaLabel = hasContent ? "Send message" : "Open chat actions";
 
   return (
     <button
@@ -33,7 +36,8 @@ export function ChatSendButton({
       className={`${styles.button} ${disabled ? "" : styles.buttonActive}`}
       disabled={disabled}
       onClick={onClick}
-      aria-label={hasContent ? "Send message" : "Add message content"}
+      aria-expanded={hasContent ? undefined : isExpanded}
+      aria-label={ariaLabel}
     >
       <Icon className={styles.icon} size={24} aria-hidden="true" />
     </button>