feat(library): import-failure modal + group sort + Android callout fix (#4345)

* fix(library): suppress Android image callout on book covers

Long-pressing a cover on Android could trigger the WebView's native
image callout at the same time as the bookshelf's own 500ms long-press
handler for multi-select, causing apparent freezes. `-webkit-touch-
callout: none` doesn't inherit, so the existing `.no-context-menu`
rule on the item container never reached the cover `<img>`. Apply the
callout suppression to descendant images/anchors and disable native
drag on the cover.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* feat(library): show modal for multi-file import failures

When a batch import yields more than one failure, the previous toast
crammed every filename onto a single line that often overflowed and
truncated. Add a dialog that lists each failed filename with its
error reason, dedupes the message into a header banner when every
file failed for the same reason, and falls back to the existing toast
for single-file failures.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* feat(library): sort manage-group modal by most recent activity

The Group Books modal listed groups in store-insertion order, which made
recently-active groups hard to find in libraries with many groups. Sort
each level desc by the newest `updatedAt` across the group's books,
propagating up the path so a recently-touched book in
`Literature/Fiction` keeps `Literature` fresh too. Extract the index as
`buildGroupNameUpdatedAt` in libraryUtils for reuse and unit testing.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* fix(library): tighten select-mode action bar and header polish

- SelectModeActions: switch the narrow-viewport grid from 3 columns to
  4 (with the delete action explicitly placed in column 2) so the icon
  set stops wrapping awkwardly on phones below ~500px.
- LibraryHeader: keep the "Select All" / "Deselect" label on a single
  line so it doesn't wrap and shove the underlying button taller.
- SetStatusAlert: drop the hover bg on the small-screen cancel button
  and rely on text-color contrast so it stops flashing a tinted disc
  on mobile taps.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

apps/readest-app/src/components/BookCover.tsx

@@ -81,6 +81,7 @@ const BookCover: React.FC<BookCoverProps> = memo<BookCoverProps>(
               alt={book.title}
               fill={true}
               loading='lazy'
+              draggable={false}
               className={clsx('cover-image crop-cover-img object-cover', imageClassName)}
               onLoad={handleImageLoad}
               onError={handleImageError}
@@ -104,6 +105,7 @@ const BookCover: React.FC<BookCoverProps> = memo<BookCoverProps>(
                 height={0}
                 sizes='100vw'
                 loading='lazy'
+                draggable={false}
                 className={clsx(
                   'cover-image fit-cover-img h-auto max-h-full w-auto max-w-full shadow-md',
                   imageClassName,