refactor(analytics): abstract analytics into provider pattern

- Add type-safe AnalyticsEvent union types
- Create AnalyticsProvider interface for pluggable analytics backends
- Implement OpenPanelProvider and RybbitProvider adapters
- Create AnalyticsTracker that fans out events to all providers
- Simplifies adding new analytics platforms in the future

src/lib/analytics/index.ts

@@ -0,0 +1,5 @@
+export { AnalyticsTracker, getTracker } from "./core/AnalyticsTracker";
+export type { AnalyticsEvent, AnalyticsProvider, ProductData, CartData, OrderData, UserData } from "./core/types";
+export { OpenPanelProvider } from "./providers/OpenPanelProvider";
+export { RybbitProvider } from "./providers/RybbitProvider";
+export { useAnalytics } from "./hooks/useAnalytics";