Moments across up to four pages: stacked in Flow, side by side in Page/Book (BL-0055)

The save sheet gets "+ Previous page" / "+ Next page" (right to left for
rtl in Page/Book) for a picture that runs over several pages. Moments
store a layout (row | column); pages the selected region does not touch
are dropped. Crops, viewer and gallery draw both layouts.

Dialogs now clean up directly instead of waiting for the "close" event,
which a backgrounded page can deliver late (a closed sheet stayed in the
page and M stopped working).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

public/manga.js

@@ -350,7 +350,7 @@
       const items = shown();
       strip.replaceChildren(...items.map((m, k) => h('button', { type: 'button', class: 'moment-thumb', title: `${momentCat(m.cat).label} · ${m.chapter.label} · ${m.missing ? 'page moved' : momentPageLabel(m.pages)}${m.note ? '\n' + m.note : ''}`,
         onclick: () => momentViewer({ mangaId: M.id, mangaTitle: M.title, list: items, index: k, onChange: changed }) },
-      momentCrop(m.pages, m.region, 200, 120),
+      momentCrop(m.pages, m.region, 200, 120, m.layout),
       h('span', { class: 'moment-thumb-cat' }, momentIcon(m.cat, 14)),
       h('span', { class: 'moment-thumb-label' }, `${m.chapter.label} · ${m.missing ? 'moved' : momentPageLabel(m.pages)}`))));
     }