feat(documents): run the vault's months side by side by default

An account that never picked an arrangement now sees the months flowing
across the width. The layout PUT stores only the fields the person chose,
so an untouched field keeps following the default while a saved choice
stays.

src/components/documents/document-timeline.tsx

@@ -31,9 +31,10 @@ import { useVirtualizer } from "@tanstack/react-virtual";
 import { useTranslations } from "@/lib/i18n/context";
 import type { InboundDocumentDto } from "@/lib/validations/inbound-documents";
 import { UploadStateCard } from "./document-card";
-import type {
-  DocumentsLayoutArrangement,
-  DocumentsLayoutView,
+import {
+  DEFAULT_DOCUMENTS_LAYOUT,
+  type DocumentsLayoutArrangement,
+  type DocumentsLayoutView,
 } from "@/lib/documents/documents-layout";
 import {
   columnsForWidth,
@@ -65,8 +66,8 @@ export function DocumentTimeline({
   highlightId,
   onPrefetch,
   timezone,
-  view = "cards",
-  arrangement = "stacked",
+  view = DEFAULT_DOCUMENTS_LAYOUT.view,
+  arrangement = DEFAULT_DOCUMENTS_LAYOUT.arrangement,
 }: {
   /** Preview tiles or compact rows (the reader's vault presentation). */
   view?: DocumentsLayoutView;