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>

README.md

@@ -151,7 +151,7 @@ completeness.
   - The middle of the page also toggles the controls (useful when a zoomed page fills the screen).
   - A horizontal swipe also turns pages on touch screens.
   - Keys: arrows, Space / PageDown, `i` = controls, `m` = save a moment, `f` = fullscreen, `?` = all shortcuts (also under Settings → User → Keyboard shortcuts).
-- **Moments:** the bookmark button in the top bar (or `m`) saves the page you are on (in Book mode the spread) as a moment. Drag over the preview to keep only a region, and pick exactly one category: Twist, Hot, Awesome, Cute, Funny or Feels, plus an optional note. The button is filled on pages that already have one. Each manga page shows *Your moments* as a strip of crops, sorted by story or by when you saved them; click one to step through them, see the full page, edit, delete or jump into the reader at that page. Moments are private to each user.
+- **Moments:** the bookmark button in the top bar (or `m`) saves the page you are on (in Book mode the spread) as a moment. A picture that runs over several pages can take up to four: *+ Previous page* / *+ Next page* add them, stacked in Flow and side by side in Page and Book. Drag over the preview to keep only a region (pages it doesn't touch are left out), and pick exactly one category: Twist, Hot, Awesome, Cute, Funny or Feels, plus an optional note. The button is filled on pages that already have one. Each manga page shows *Your moments* as a strip of crops, sorted by story or by when you saved them; click one to step through them, see the full page, edit, delete or jump into the reader at that page. Moments are private to each user.
 - **Controls stay out of the way:** they hide as soon as you turn a page or scroll, and come back only with a tap (middle of the page or beside it) or `i`. Scrolling up never brings them back. The first time they hide, a short hint says so.
 - **Controls:** the top bar has a chapter picker with every chapter of the manga, grouped by book, with ✓ for read ones. The bottom bar has the page slider, the mode switch, Shift, zoom, the version picker and previous/next chapter.
 - **Loading:** the next pages (next 3 in Page mode, next 2 spreads in Book mode) are downloaded and decoded in advance, so page turns don't flash. A page that still isn't there shows a spinner. On phones, "Add to home screen" opens the app without browser bars, and the ⛶ button (where supported) goes fullscreen.