Build Widgets & Home-Screen Integration

Background: Native [platform] app, [SwiftUI / Compose]. I want to add:
[home-screen widget / lock-screen widget / app shortcut / quick action /
Live Activity]. What it shows or does: [describe].

Use case: Build the home-screen integration and keep it in sync with the
main app's data.

Implementation details:
- iOS: WidgetKit widgets (SwiftUI), timeline provider and refresh budget,
  sharing data via an App Group, deep-linking from the widget; App
  Shortcuts / Siri intents or Home Screen quick actions if relevant.
  Android: Glance/App Widget, update scheduling, and App Shortcuts.
- The data-sharing mechanism between app and widget (App Group / shared
  storage) and keeping it fresh within the platform's refresh limits
- Tapping the widget deep-links into the right screen (ties to 7.5 / 2.4)
- Multiple sizes/families and their layouts
- Graceful placeholder/redacted state before data loads

Layer & dependencies: The widget reads from shared storage written by the
app's data layer; it does not run the full app stack.

Deliverable: The widget implementation with its sizes, the timeline/
update strategy within refresh limits, the app-to-widget data-sharing setup,
the deep-link-on-tap wiring, and the placeholder state.