fix: codebase audit fixes — safety, accessibility, and production hygiene

Address 16 issues from external audit:
- Move StoreKit transaction listener ownership to StoreManager singleton with proper deinit
- Remove noisy VoiceOver announcements, add missing accessibility on StatPill and BootstrapLoadingView
- Replace String @retroactive Identifiable with IdentifiableShareCode wrapper
- Add crash guard in AchievementEngine getContributingVisitIds + cache stadium lookups
- Pre-compute GamesHistoryViewModel filtered properties to avoid redundant SwiftUI recomputation
- Remove force-unwraps in ProgressMapView with safe guard-let fallback
- Add diff-based update gating in ItineraryTableViewWrapper to prevent unnecessary reloads
- Replace deprecated UIScreen.main with UIWindowScene lookup
- Add deinit task cancellation in ScheduleViewModel and SuggestedTripsGenerator
- Wrap ~234 unguarded print() calls across 27 files in #if DEBUG

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

SportsTime/Core/Theme/AnimatedComponents.swift

@@ -198,6 +198,7 @@ struct StatPill: View {
         HStack(spacing: 6) {
             Image(systemName: icon)
                 .font(.caption)
+                .accessibilityHidden(true)
             Text(value)
                 .font(.footnote)
         }

SportsTime/Core/Theme/SportSelectorGrid.swift

@@ -269,7 +269,9 @@ extension SportSelectorGrid where Content == SportToggleButton {
 
         SportSelectorGrid { sport in
             SportActionButton(sport: sport) {
+                #if DEBUG
                 print("Selected \(sport.rawValue)")
+                #endif
             }
         }
     }