Align date/time column in upcoming widget

Give the date column a fixed width (7rem) and right-align it so
entries with different date formats (date-only vs datetime) line up.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/dashboard/UpcomingWidget.tsx

@@ -48,7 +48,7 @@ export default function UpcomingWidget({ items, days = 7 }: UpcomingWidgetProps)
                   >
                     <Icon className={cn('h-3.5 w-3.5 shrink-0', config.color)} />
                     <span className="text-sm font-medium truncate flex-1 min-w-0">{item.title}</span>
-                    <span className="text-xs text-muted-foreground shrink-0 whitespace-nowrap tabular-nums">
+                    <span className="text-xs text-muted-foreground shrink-0 whitespace-nowrap tabular-nums w-[7rem] text-right">
                       {item.datetime
                         ? format(new Date(item.datetime), 'MMM d, h:mm a')
                         : format(new Date(item.date), 'MMM d')}