feat(trip): redesign add custom item UI with polished visuals

Replace confusing dual-mode AddItemSheet with streamlined QuickAddItemSheet:
- Single flow with optional location (vs Search/Custom toggle)
- Card-based layout with shadows, borders, and theme colors
- Enhanced CategoryPicker with emoji circles and press animations
- Separate PlaceSearchSheet for focused location search
- Improved header button with capsule style and accessibility labels

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

SportsTime/Features/Trip/Views/ItineraryTableViewController.swift

@@ -1059,17 +1059,16 @@ struct DaySectionHeaderView: View {
             
             Spacer()
             
-            // Add button (right-aligned)
+            // Add button (right-aligned, bordered capsule for discoverability)
             Button(action: onAddTapped) {
-                HStack(spacing: Theme.Spacing.xs) {
-                    Image(systemName: "plus.circle.fill")
-                        .foregroundStyle(Theme.warmOrange.opacity(0.6))
-                    Text("Add")
-                        .font(.subheadline)
-                        .foregroundStyle(Theme.textMuted(colorScheme))
-                }
+                Label("Add", systemImage: "plus")
+                    .font(.subheadline.weight(.medium))
             }
-            .buttonStyle(.plain)
+            .buttonStyle(.bordered)
+            .buttonBorderShape(.capsule)
+            .tint(Theme.warmOrange)
+            .accessibilityLabel("Add item to Day \(dayNumber)")
+            .accessibilityHint("Add restaurants, activities, or notes to this day")
         }
         .padding(.horizontal, Theme.Spacing.lg)
         .padding(.top, Theme.Spacing.lg)  // More space above for section separation