ui: make Featured Trips carousel scroll edge-to-edge

Use contentMargins on horizontal ScrollView so cards start inset but
scroll to screen edges. Pad headers and error states individually.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

SportsTime/Features/Home/Views/LoadingTripsView.swift

@@ -20,10 +20,12 @@ struct LoadingTripsView: View {
                     .foregroundStyle(Theme.textPrimary(colorScheme))
                 Spacer()
             }
+            .padding(.horizontal, Theme.Spacing.md)
 
             // Loading indicator with message
             LoadingSpinner(size: .small, label: message)
                 .padding(.vertical, Theme.Spacing.xs)
+                .padding(.horizontal, Theme.Spacing.md)
 
             // Placeholder cards
             ScrollView(.horizontal, showsIndicators: false) {
@@ -33,6 +35,7 @@ struct LoadingTripsView: View {
                     }
                 }
             }
+            .contentMargins(.horizontal, Theme.Spacing.md, for: .scrollContent)
         }
     }
 }