Feature flags integration

[ibrahimcesar]

Description

Integrate feature flags with telemetry tracking for rollout management.

Features

• Feature flag evaluation
• Flag exposure tracking
• Percentage rollouts
• User segment targeting
• Kill switch support

Example Usage

```rust
if telemetry.is_enabled("new-export-format") {
// New implementation
} else {
// Existing implementation
}
```

Integrations to Consider

• LaunchDarkly
• Split
• Unleash
• Custom/self-hosted flags

Acceptance Criteria

• Simple flag evaluation API
• Automatic exposure tracking
• Works offline (cached flags)