Remove old PostHogAnalytics singleton and replace with guide-based
two-file architecture: AnalyticsManager (singleton wrapper with super
properties, session replay, opt-out, subscription funnel) and
AnalyticsEvent (type-safe enum with associated values).
Key changes:
- New API key, self-hosted analytics endpoint
- All 19 events ported to type-safe AnalyticsEvent enum
- Screen tracking via AnalyticsManager.Screen enum + SwiftUI modifier
- Remove all identify() calls — fully anonymous analytics
- Add lifecycle hooks: flush on background, update super properties on foreground
- Add privacy opt-out toggle in Settings
- Subscription funnel methods ready for IAP integration
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
