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/Features/Trip/Views/AddItem/QuickAddItemSheet.swift

@@ -734,7 +734,9 @@ private struct PressableStyle: ButtonStyle {
         day: 1,
         existingItem: nil
     ) { item in
+        #if DEBUG
         print("Saved: \(item)")
+        #endif
     }
     .preferredColorScheme(.light)
 }
@@ -745,7 +747,9 @@ private struct PressableStyle: ButtonStyle {
         day: 3,
         existingItem: nil
     ) { item in
+        #if DEBUG
         print("Saved: \(item)")
+        #endif
     }
     .preferredColorScheme(.dark)
 }
@@ -770,6 +774,8 @@ private struct PressableStyle: ButtonStyle {
         day: existing.day,
         existingItem: existing
     ) { item in
+        #if DEBUG
         print("Updated: \(item)")
+        #endif
     }
 }