Resolves issue #3 where aircraft age field was always showing 0 seconds.
Backend Changes:
- Fix MarshalJSON in merger.go to calculate age dynamically using time.Since(a.LastUpdate)
- Add comprehensive tests for age calculation in merger_test.go
Frontend Changes:
- Add calculateAge() utility method to both aircraft-manager.js and ui-manager.js
- Update popup content and aircraft table to use client-side age calculation
- Implement real-time age updates every second in app.js
- Add updateOpenPopupAges() function to refresh popup displays
Key Benefits:
- Aircraft age now shows actual seconds since last transmission
- Real-time updates in UI without requiring new WebSocket data
- Proper data staleness indicators for aviation tracking
- No additional server load - client-side calculation using last_update timestamp
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
