WidgetKit and ActivityKit Build home screen widgets, Lock Screen widgets, Live Activities, Dynamic Island presentations, Control Center controls, and StandBy surfaces for iOS 26+. See references/widgetkit-advanced.md for timeline strategies, push-based updates, Xcode setup, and advanced patterns. Contents - Workflow - Widget Protocol and WidgetBundle - Configuration Types - TimelineProvider - AppIntentTimelineProvider - Widget Families - Interactive Widgets (iOS 17+) - Live Activities and Dynamic Island - Control Center Widgets (iOS 18+) - Lock Screen Widgets - StandBy Mode - Design Patterns…