1. ThemeProgressViewModifier to replace content with a progress view
while a condition is active
2. ThemeEmptyContentModifier to replace content with a message if an
empty condition is met
3. Replace .opacity(bool ? 1.0 : 0.0) with .opaque(bool)
Reuse:
- 1 in PaywallView and DonateView
- 2 in ProfileContainerView
- Use StoreKit views when available
- Offer one-time purchase
- Recurring subscriptions for all features
- Restore purchases
Remove .siri (Shortcuts), now free.
Closes#819Closes#469