fix: standardize trip name display with arrow separators app-wide

- Add `displayName` computed property to Trip model that always
  generates city list with " → " separator for consistent display
- Replace all `trip.name` usages with `trip.displayName` in UI files
- Update SuggestedTripsGenerator to use " → " separator
- Update PDFGenerator to use displayName for PDF titles

This ensures all trip names display consistently regardless of when
the trip was created or how the name was originally stored.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

SportsTime/Features/Home/Views/Variants/Glassmorphism/HomeContent_Glassmorphism.swift

@@ -224,7 +224,7 @@ struct HomeContent_Glassmorphism: View {
                 }
             }
 
-            Text(trip.name)
+            Text(trip.displayName)
                 .font(.system(size: 16, weight: .semibold, design: .rounded))
                 .foregroundStyle(colorScheme == .dark ? .white : Color(white: 0.15))
                 .lineLimit(2)
@@ -306,7 +306,7 @@ struct HomeContent_Glassmorphism: View {
                                 }
 
                                 VStack(alignment: .leading, spacing: 4) {
-                                    Text(trip.name)
+                                    Text(trip.displayName)
                                         .font(.system(size: 15, weight: .medium, design: .rounded))
                                         .foregroundStyle(colorScheme == .dark ? .white : Color(white: 0.15))