fix(ui): report the shown carousel step so report flows react (#3353)

fluxer_app/src/features/ui/stepped_carousel/SteppedCarousel.test.tsx

@@ -0,0 +1,35 @@
+// @vitest-environment happy-dom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {SteppedCarousel} from '@app/features/ui/stepped_carousel/SteppedCarousel';
+import {act} from 'react';
+import {createRoot} from 'react-dom/client';
+import {expect, test, vi} from 'vitest';
+
+(globalThis as {IS_REACT_ACT_ENVIRONMENT?: boolean}).IS_REACT_ACT_ENVIRONMENT = true;
+
+test('reports the step whose pane was just shown', () => {
+	const container = document.createElement('div');
+	document.body.append(container);
+	const root = createRoot(container);
+	const onStepShown = vi.fn();
+	const render = (step: 'loading' | 'ready') =>
+		act(() => {
+			root.render(
+				<SteppedCarousel
+					step={step}
+					steps={[step]}
+					onStepShown={onStepShown}
+					data-flx="ui.stepped-carousel.test.carousel"
+				>
+					<span data-flx="ui.stepped-carousel.test.step">{step}</span>
+				</SteppedCarousel>,
+			);
+		});
+	render('loading');
+	expect(onStepShown).toHaveBeenLastCalledWith('loading');
+	render('ready');
+	expect(onStepShown).toHaveBeenLastCalledWith('ready');
+	act(() => root.unmount());
+	container.remove();
+});

fluxer_app/src/features/ui/stepped_carousel/SteppedCarousel.tsx

@@ -125,7 +125,8 @@ export function SteppedCarousel<Step extends string>({
 	const paneRef = useRef<HTMLDivElement | null>(null);
 	const pendingFocusRequestRef = useRef(0);
 	const handledFocusRequestRef = useRef(0);
-	const stepShownRef = useRef({step, onStepShown});
+	const onStepShownRef = useRef(onStepShown);
+	const paneStep = step;
 	const measureNode = useCallback((node: HTMLElement) => {
 		const offsetHeight = node.offsetHeight;
 		const scrollHeight = node.scrollHeight;
@@ -146,7 +147,7 @@ export function SteppedCarousel<Step extends string>({
 					(node.querySelector<HTMLElement>(focusableSelector) ?? node).focus({preventScroll: true});
 				}
 			}
-			stepShownRef.current.onStepShown?.(stepShownRef.current.step);
+			onStepShownRef.current?.(paneStep);
 			let observer: ResizeObserver | null = null;
 			if (typeof ResizeObserver !== 'undefined') {
 				observer = new ResizeObserver(() => {
@@ -163,13 +164,13 @@ export function SteppedCarousel<Step extends string>({
 				}
 			};
 		},
-		[measureNode],
+		[measureNode, paneStep],
 	);
 	useLayoutEffect(() => {
 		pendingFocusRequestRef.current = model.focusRequestId;
 	}, [model.focusRequestId]);
 	useLayoutEffect(() => {
-		stepShownRef.current = {step, onStepShown};
+		onStepShownRef.current = onStepShown;
 	});
 	return (
 		<motion.div