Fix the blank window after an export

Every successful export left the window blank and unresponsive, so the app had to be killed. The "Saved to ..." notice
(and the export-failed notice) held buttons inside a Carbon InlineNotification. Carbon throws "component should have no
interactive child nodes" in an effect, and an uncaught throw makes React unmount the whole tree. Found by driving the
real debug binary through WebKitWebDriver: the page body was empty and the error listener showed that throw.

- The buttons now sit beside the notice, and the failed-export notice uses ActionableNotification's own Retry action.
- ErrorBoundary around the app (reload screen instead of a blank window) and around each export notice.
- A lint test that fails if a Carbon notification wraps an interactive element.
- The real-webview self-test mounts the saved and failed notices and fails on an uncaught React error, and issues and
  exports a second invoice after the first.

Claude-Session: https://claude.ai/code/session_01PZypiWDfMkDTeEPeXjRhW5

src/views/NewInvoice.tsx

@@ -61,6 +61,7 @@ import { useInvoicePdf } from "../hooks/useInvoicePdf";
 import { useInvoiceExport } from "../hooks/useInvoiceExport";
 import { autoPushIssued } from "../lib/erpnextUi";
 import ExportButton, { ExportModePicker } from "../components/ExportButton";
+import ErrorBoundary from "../components/ErrorBoundary";
 import ExportFeedback from "../components/ExportFeedback";
 import { createExportDeps } from "../lib/exportDeps";
 import { issueAndArchive, renderAndArchive } from "../lib/exportFlow";
@@ -784,7 +785,9 @@ export default function NewInvoice({ settings, onSettingsChange, active, onActiv
                   onActionButtonClick={() => void retryArchive()}
                 />
               ) : null}
-              <ExportFeedback exp={exp} />
+              <ErrorBoundary fallback={(e) => <p className="voiced-muted">The export result could not be shown ({e.message}). The PDF was still saved.</p>}>
+                <ExportFeedback exp={exp} />
+              </ErrorBoundary>
               <div className="voiced-header-action" style={{ flexWrap: "wrap", marginTop: "0.5rem" }}>
                 <ExportButton onExport={(mode) => void exp.start(exportable, mode, "original")} disabled={busy} />
                 <Button kind="tertiary" renderIcon={Copy} onClick={duplicateAsNew} disabled={busy}>