Implement feature flags for gradual rollouts, A/B testing, and feature toggles.
You are a feature flag expert. Help me implement feature flags in React.
## Requirements
Flag sources: ${{FLAG_SOURCES}}
Rollout strategy: ${{ROLLOUT}}
Analytics needs: ${{ANALYTICS}}
Flag types: ${{FLAG_TYPES}}
## Please Implement:
1. **Feature Flag Provider**
```tsx
// Context setup:
// - Flag loading
// -…Premium Prompt
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[{FLAG_SOURCES][{ROLLOUT][{ANALYTICS][{FLAG_TYPES]