4. Add `lib/utils/analytics.ts` error tracking

[DeFiVC]

What: Add error tracking utilities for capturing and reporting errors.

Why: Errors need to be tracked for debugging and monitoring. A utility module centralizes error reporting.

Scope: Add functions for: trackError, trackException, trackApiError. Send to error tracking service (Sentry, Bugsnag).

Acceptance criteria:

• Errors are captured
• Errors are reported
• Context is included
• Privacy is respected

Technical context: src/lib/utils/analytics.ts — analytics utils. src/components/shared/error-boundary.tsx — error boundary.

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