fix(app): smooth the fluxer.com migration and expired re-login (#3019)

fluxer_app/src/app/BootstrapErrorMount.tsx

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {initI18n} from '@app/app/I18n';
+import {BootstrapErrorScreen} from '@app/features/app/components/BootstrapErrorScreen';
+import {AppI18nProvider} from '@app/features/i18n/components/AppI18nProvider';
+import {Logger} from '@app/features/platform/utils/AppLogger';
+import {i18n} from '@lingui/core';
+import ReactDOM from 'react-dom/client';
+
+const logger = new Logger('index');
+
+export async function reportBootstrapError(error: unknown): Promise<void> {
+	const normalized = error instanceof Error ? error : new Error(String(error));
+	logger.error('Failed to bootstrap app:', normalized);
+	const container = document.getElementById('root');
+	if (!container) {
+		throw new Error('Missing #root element');
+	}
+	await initI18n();
+	ReactDOM.createRoot(container).render(
+		<AppI18nProvider i18n={i18n}>
+			<BootstrapErrorScreen error={normalized} data-flx="index.bootstrap-error-screen" />
+		</AppI18nProvider>,
+	);
+}