fix(ios): adopt smaller font size for small device (#13715)

This pull request makes minor adjustments to the iOS frontend app,
focusing on UI fine-tuning and improving type safety for concurrency.
The most notable changes are a small font size adjustment in the paywall
badge, marking an enum as `Sendable` for safer concurrency, and removing
a StoreKit configuration reference from the Xcode scheme.

UI adjustments:
* Reduced the font size for the badge text in `PackageOptionView` from
12 to 10 for a more refined appearance.

Concurrency and type safety:
* Added the `Sendable` protocol conformance to the `SKUnitCategory` enum
to ensure it can be safely used across concurrency boundaries.

Project configuration:
* Removed the `StoreKitConfigurationFileReference` from the
`App.xcscheme`, which may help streamline scheme configuration or
prevent unnecessary StoreKit file usage during app launch.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- Style
- Tweaked paywall option badge text size for a cleaner, more polished
look.

- Refactor
- Improved concurrency safety in underlying models to enhance stability.

- Chores
- Removed a development-only StoreKit configuration from the iOS debug
launch setup.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/apps/ios/App/App.xcodeproj/xcshareddata/xcschemes/App.xcscheme

@@ -50,9 +50,6 @@
             ReferencedContainer = "container:App.xcodeproj">
          </BuildableReference>
       </BuildableProductRunnable>
-      <StoreKitConfigurationFileReference
-         identifier = "../App/Products.storekit">
-      </StoreKitConfigurationFileReference>
    </LaunchAction>
    <ProfileAction
       buildConfiguration = "Release"