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/Planning/Engine/GameDAGRouter.swift

@@ -246,7 +246,9 @@ enum GameDAGRouter {
         // Step 6: Final diversity selection
         let finalRoutes = selectDiverseRoutes(routesWithAnchors, stadiums: stadiums, maxCount: maxOptions)
 
+        #if DEBUG
         print("🔍 DAG: Input games=\(games.count), beam=\(beam.count), withAnchors=\(routesWithAnchors.count), final=\(finalRoutes.count)")
+        #endif
 
         return finalRoutes
     }
@@ -586,10 +588,12 @@ enum GameDAGRouter {
         let feasible = drivingHours <= maxDrivingHoursAvailable && drivingHours <= availableHours
 
         // Debug output for rejected transitions
+        #if DEBUG
         if !feasible && drivingHours > 10 {
             print("🔍 DAG canTransition REJECTED: \(fromStadium.city) → \(toStadium.city)")
             print("🔍   drivingHours=\(String(format: "%.1f", drivingHours)), daysBetween=\(daysBetween), maxAvailable=\(String(format: "%.1f", maxDrivingHoursAvailable)), availableHours=\(String(format: "%.1f", availableHours))")
         }
+        #endif
 
         return feasible
     }