Gate the company-settings preview page behind Draft Mode

Unlike the email-templates preview (marketing copy), this page shows
real bank/address details once filled in — it must not render for an
unauthenticated visitor who finds the URL.

README.md

@@ -408,9 +408,12 @@ updating as the admin edits `sellerName`/address/`taxRatePercent`/
 
 - **`app/company-settings-preview/page.tsx`** + **`components/LiveCompanySettingsPreviewClient.tsx`**
   — same entrypoint pattern as `/email-preview/[type]` (Draft Mode via
-  `app/api/preview/route.ts`, never a real visitor destination), but no
-  `[type]` segment — there's only one kind of document here, unlike the 6
-  email types.
+  `app/api/preview/route.ts`), but no `[type]` segment — there's only one
+  kind of document here, unlike the 6 email types. **Actually gated on
+  `draftMode().isEnabled`** (calls `notFound()` otherwise), unlike
+  `/email-preview` — this data includes a real bank IBAN/address once
+  filled in, not just marketing email copy, so it must not render for an
+  unauthenticated visitor who happens to find the URL.
 - **`@react-pdf/renderer`'s `<PDFViewer>`** (not `renderToBuffer()`) is
   what makes this a *live* preview rather than a static download — it's a
   browser-only component that renders a `Document` straight into an

app/company-settings-preview/page.tsx

@@ -1,5 +1,6 @@
 import type { Metadata } from "next";
 import { draftMode } from "next/headers";
+import { notFound } from "next/navigation";
 import { getCompanySettings, type CompanySettings } from "../lib/payload";
 import { LiveCompanySettingsPreviewClient } from "./components/LiveCompanySettingsPreviewClient";
 
@@ -22,13 +23,18 @@ const FALLBACK: CompanySettings = {
 
 // Entered exclusively via CompanySettings.ts's admin.livePreview.url (a
 // Payload-admin-only iframe target, see buildPreviewUrl()/api/preview) —
-// not a page a real visitor would ever land on. Unlike email-templates
-// there's no draft/published distinction here (company-settings has no
-// content-versioning concept, it's just the current row) — the initial
-// fetch is the same live data getCompanySettings() always returns,
-// useLivePreview() takes over from there as the admin edits fields.
+// gated on Draft Mode actually being enabled, unlike email-templates'
+// preview: this data includes a real bank IBAN/address once filled in,
+// not just marketing email copy, so this page must not render for an
+// unauthenticated visitor who happens to find the URL. Unlike
+// email-templates there's no draft/published distinction in the data
+// itself (company-settings has no content-versioning concept, it's just
+// the current row) — the initial fetch is the same live data
+// getCompanySettings() always returns, useLivePreview() takes over from
+// there as the admin edits fields.
 export default async function CompanySettingsPreviewPage() {
-  await draftMode();
+  const draft = await draftMode();
+  if (!draft.isEnabled) notFound();
   const initialSettings = (await getCompanySettings()) ?? FALLBACK;
   return <LiveCompanySettingsPreviewClient initialSettings={initialSettings} />;
 }