Feature Flags Infrastructure

Help me implement feature flags for my application.

Requirements:
- Platform preference: [LaunchDarkly/Unleash/Flagsmith/custom]
- Application types: [web/mobile/backend]
- Scale: [users, feature flags count]
- Requirements: [A/B testing, gradual rollout, targeting]

Feature flag setup:
1. Infrastructure
   - Feature flag service deployment
   - SDK integration
   - High availability setup
   - Caching strategy

2. Flag management
   - Flag lifecycle (create, update, archive)
   - Environment management
   - Targeting rules
   - Percentage rollouts

3. Integration patterns
   - Backend SDK setup
   - Frontend SDK setup
   - Edge/CDN integration
   - CI/CD flag automation

4. Operations
   - Flag audit logging
   - Monitoring and alerts
   - Emergency kill switches
   - Technical debt tracking

Include:
- Service deployment configuration
- SDK integration examples
- Flag management workflows
- Operational procedures