fix(web): portal the natal board peek without effect setState

Quality gate lint failed on setHeaderSlot inside useLayoutEffect, so staging never published. Pass the header mount node from a callback ref instead.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/conversational-birth-time-rectification.tsx

@@ -36,6 +36,7 @@ export type ConversationalBirthTimeRectificationProps = Readonly<{
   onStartConsultation?: () => void;
   pendingConsultationQuestion?: string | null;
   onRestart?: () => void;
+  headerSlot: HTMLElement | null;
 }>;
 
 export function ConversationalBirthTimeRectification(props: ConversationalBirthTimeRectificationProps) {

frontend/src/components/rectification-agentic-chat.tsx

@@ -142,6 +142,7 @@ type RectificationAgenticChatProps = Readonly<{
   onStartConsultation?: () => void;
   pendingConsultationQuestion?: string | null;
   onRestart?: () => void;
+  headerSlot: HTMLElement | null;
 }>;
 
 type RenderMessage = ChatMessageView & {
@@ -240,6 +241,7 @@ export function RectificationAgenticChat(props: RectificationAgenticChatProps) {
     onStartConsultation,
     pendingConsultationQuestion,
     onRestart,
+    headerSlot,
   } = props;
 
   const [messages, setMessages] = useState<RenderMessage[]>(() => messagesFromTurns(initialTurns));
@@ -263,14 +265,9 @@ export function RectificationAgenticChat(props: RectificationAgenticChatProps) {
   const [compactBoard, setCompactBoard] = useState(false);
   const [boardOpen, setBoardOpen] = useState(false);
   const [boardDiff, setBoardDiff] = useState(() => diffRectificationBoard(null, null));
-  const [headerSlot, setHeaderSlot] = useState<HTMLElement | null>(null);
   const boardId = useId();
   const boardTitleId = useId();
 
-  useLayoutEffect(() => {
-    setHeaderSlot(document.querySelector("[data-rectification-header-slot]"));
-  }, []);
-
   useLayoutEffect(() => {
     const query = window.matchMedia(`(max-width: ${RECTIFICATION_BOARD_SPLIT_MIN_PX - 1}px)`);
     const update = () => {