bugfix: render single day in ItineraryDay instead of mapping all itinerary days

[nleiby]

Currently, adding a day to the itinerary adds all days for each day in the itinerary (screen shot and screen capture attached)

This PR:

1. Adds 3 lines before the return: dayIndex, date, and const { notes, locations } = day.
2. Returns a single root
   (no <> or .map()).
3. Uses dayIndex + 1 for the heading, day.id in TravelTime and in open("addItineraryLocation", { dayId: day.id }).

Current behavior:

Screen.Recording.2026-02-01.at.4.05.49.PM.mov