Update PDFGenerator to accept optional ItineraryItem array and render
items in user-specified sortOrder within each day. Adds support for:
- Custom items with icon, title, time, and address
- Travel segments from ItineraryItem (not just TravelSegment)
- Fallback to derived order when no itinerary items provided
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>