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/ScenarioBPlanner.swift

@@ -468,7 +468,9 @@ final class ScenarioBPlanner: ScenarioPlanner {
             }
         }
 
+        #if DEBUG
         print("🔍 ScenarioB Regional: Anchor games in regions: \(anchorRegions.map { $0.shortName })")
+        #endif
 
         // Run beam search for each region that has anchor games
         // (Other regions without anchor games would produce routes that don't satisfy anchors)
@@ -490,7 +492,9 @@ final class ScenarioBPlanner: ScenarioPlanner {
                 stopBuilder: buildStops
             )
 
+            #if DEBUG
             print("🔍 ScenarioB Regional: \(region.shortName) produced \(regionRoutes.count) routes")
+            #endif
             allRoutes.append(contentsOf: regionRoutes)
         }