Add a Custom swatch to the appearance settings accent color grid,
backed by a hex value stored in settings (synced via iCloud like the
rest). iOS uses the native ColorPicker wheel; macOS uses a circular
swatch that opens NSColorPanel, since the SwiftUI color well looks out
of place among the circles. All accent consumers now read the resolved
color through SettingsManager.resolvedAccentColor.
The indigo preset is retired from the grid but kept in the enum, so
users who selected it keep their color until they pick another one.
Claude-Session: https://claude.ai/code/session_0154KH8RAVAvm6iVanhmoW8o
- Fix BGTaskScheduler assertion crash on Mac Catalyst by guarding all
iOS background task APIs with isMacCatalystApp check
- Fix iPad popover crash in UIPopoverPresentationController by adding
.presentationCompactAdaptation(.sheet) to all 27 confirmationDialogs
- Fix SwiftData assertion crash when accessing deleted Bookmark model
properties during SwiftUI hit testing in BookmarkRowView
- Fix UICollectionView invalid item count crash on queue swipe-to-delete
by using ID-based removal with withAnimation instead of stale index
- Fix Range crash in storyboard download when storyboardCount is zero