Multi-day flight scheduling with timezone awareness

This feature request highlights a critical gap in TREK's core travel planning logic: the inability to accurately represent multi-day flights, especially those crossing timezones. Current implementation likely assumes single-day events, leading to inaccurate itinerary displays for international travel. The proposed solution, integrating timezones into departure/arrival, is a standard requirement for any robust travel management system. Failure to address this limits TREK's utility for long-haul or complex international trips, directly impacting its market competitiveness against more sophisticated travel planners. This is a foundational data model enhancement necessary for realistic trip visualization.