Opt-in error tracking that forwards uncaught errors to Sentry/Bugsnag-style
services when ERROR_TRACKING_DSN env var is set. Without DSN, disabled.
Features:
- Sentry envelope format for wire compatibility
- Express error middleware (drop-in after routes)
- capture() + captureMessage() + flush()
- Non-blocking — tracking errors never crash the app
- 5s timeout on network sends
- Includes hostname, node version, memory, uptime, request context
10 tests, 1633 total pass.
