Colorful shortcut cards now color by grid position instead of shortcut
identity, so colors stay in the same slot when shortcuts are reordered.
Adds a Palette option (Classic default, plus Sunset, Meadow, Berry,
Grape) and a Custom palette with a swatch-list editor (ColorPicker + hex
fields) and a switchable comma-separated text field. Color is resolved
per position and wraps by palette length, wired via a new
homeShortcutColorfulColor environment value and a Color(hex:) extension.
Sheet dismiss buttons rendered as an iOS-style circular glass "X" on
macOS 26, which looks foreign on the desktop. Add a shared
sheetCloseToolbarItem helper that renders a native text "Close" button
on macOS while keeping the compact icon-only xmark on iOS/tvOS, and
replace the ~14 duplicated inline close buttons across sheets with it.
Extract shared TimeInterval.formattedAsTimestamp replacing 8 identical
formatTime/formattedTime implementations across player views. Remove
unused currentTime parameter from GestureSeekPreviewView. Consolidate
duplicated geometry math in MacOSControlBar into seekPreviewPosition().
