revenuecat-entitlements-gate: check a RevenueCat entitlement

Use this skill when the user wants to decide whether to show or hide a feature based on an active RevenueCat entitlement. The skill covers the one shot check and the reactive listener; it does not cover purchasing (see revenuecat-purchase-flow) or auth (revenuecat-identify-user).

1. Detect the platform

Inspect the working directory and pick the first match, from top to bottom:

1. React Native: package.json has a react-native-purchases entry, or react-native as a dependency → read platforms/react-native.md. If expo is also a dependency, note it as an Expo project.
2. Flutter: pubspec.yaml exists at the project root → read platforms/flutter.md.
3. Kotlin Multiplatform: build.gradle.kts contains a kotlin { … } multiplatform source sets block, or depends on com.revenuecat.purchases:purchases-kmp* → read platforms/kmp.md.
4. Android (native): build.gradle(.kts) applies com.android.application (and is not KMP) → read platforms/android.md.
5. iOS (native): Package.swift, *.xcodeproj, *.xcworkspace, or Podfile at the project root → read platforms/ios.md.

If several match (e.g. an ios/ folder inside a Flutter project), pick the outermost project, the one that owns the build. If still ambiguous, ask the user which platform they want to configure.

2. Shared concepts (all platforms)

• Check the entitlement identifier, not the product ID. The identifier (for example "premium") is configured in the RevenueCat dashboard and mapped to one or more products. Using the entitlement lets you change products, prices, and stores without touching app code.