♿️(frontend) add focus restore store

Create Zustand store to track last focused element
and restore focus after overlay close. DropdownMenu
auto-stores trigger ref when an option is clicked.

src/frontend/apps/impress/src/components/DropButton.tsx

@@ -9,6 +9,7 @@ import { Button, Popover } from 'react-aria-components';
 import styled, { css } from 'styled-components';
 
 import { useCunninghamTheme } from '@/cunningham';
+import { useFocusStore } from '@/stores';
 
 import { BoxProps } from './Box';
 
@@ -70,8 +71,9 @@ export const DropButton = ({
   const { themeTokens } = useCunninghamTheme();
   const font = themeTokens['font']?.['families']['base'];
   const [isLocalOpen, setIsLocalOpen] = useState(isOpen);
+  const addLastFocus = useFocusStore((state) => state.addLastFocus);
 
-  const triggerRef = useRef(null);
+  const triggerRef = useRef<HTMLButtonElement | null>(null);
 
   useEffect(() => {
     setIsLocalOpen(isOpen);
@@ -86,7 +88,10 @@ export const DropButton = ({
     <>
       <StyledButton
         ref={triggerRef}
-        onPress={() => onOpenChangeHandler(true)}
+        onPress={() => {
+          addLastFocus(triggerRef.current);
+          onOpenChangeHandler(true);
+        }}
         aria-label={label}
         data-testid={testId}
         $css={css`

src/frontend/apps/impress/src/stores/index.ts

@@ -1,2 +1,3 @@
 export * from './useBroadcastStore';
+export * from './useFocusStore';
 export * from './useResponsiveStore';

src/frontend/apps/impress/src/stores/useFocusStore.tsx

@@ -0,0 +1,23 @@
+import { create } from 'zustand';
+
+interface UseFocusStore {
+  lastFocusedElement: HTMLElement | null;
+  addLastFocus: (target: HTMLElement | null) => void;
+  restoreFocus: () => void;
+}
+
+export const useFocusStore = create<UseFocusStore>((set, get) => ({
+  lastFocusedElement: null,
+  addLastFocus: (target) => set({ lastFocusedElement: target }),
+  restoreFocus: () => {
+    const { lastFocusedElement } = get();
+    if (!lastFocusedElement) {
+      return;
+    }
+
+    requestAnimationFrame(() => {
+      lastFocusedElement.focus();
+    });
+    set({ lastFocusedElement: null });
+  },
+}));