All datetime values are stored in UTC but were displaying raw UTC times
to users, causing confusion (e.g., 10:00 Bucharest showing as 08:00).
This implements proper timezone conversion throughout the app using each
user's profile timezone setting.
Changes:
- Frontend: Replace local formatters with timezone-aware utilities
- Backend: Add timezone conversion to PUT /bookings endpoint
- FullCalendar: Configure to display events in user timezone
- Fix edit modal to preserve times when editing bookings
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
b93b8d2e71