fix: 13 audit fixes — memory, concurrency, performance, accessibility

Critical:
- ProgressViewModel: use single stored ModelContext instead of creating
  new ones per operation (deleteVisit silently no-op'd)
- ProgressViewModel: convert expensive computed properties to stored
  with explicit recompute after mutations (3x recomputation per render)

Memory:
- AnimatedSportsIcon: replace recursive GCD asyncAfter with Task loop,
  cancelled in onDisappear (19 unkillable timer chains)
- ItineraryItemService: remove [weak self] from actor Task (semantically
  wrong, silently drops flushPendingUpdates)
- VisitPhotoService: remove [weak self] from @MainActor Task closures

Concurrency:
- StoreManager: replace nested MainActor.run{Task{}} with direct await
  in listenForTransactions (fire-and-forget race)
- VisitPhotoService: move JPEG encoding/file writing off MainActor via
  nonisolated static helper + Task.detached
- SportsIconImageGenerator: replace GCD dispatch with Task.detached for
  structured concurrency compliance

Performance:
- Game/RichGame: cache DateFormatters as static lets instead of
  allocating per-call (hundreds of allocations in schedule view)
- TripDetailView: wrap ~10 routeWaypoints print() in #if DEBUG, remove
  2 let _ = print() from TripMapView.body (fires every render)

Accessibility:
- GameRow: add combined VoiceOver label (was reading abbreviations
  letter-by-letter)
- Sport badges: add accessibilityLabel to prevent SF symbol name readout
- SportsTimeApp: post UIAccessibility.screenChanged after bootstrap
  completes so VoiceOver users know app is ready

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

SportsTime/Features/Settings/SportsIconImageGenerator.swift

@@ -240,14 +240,14 @@ struct SportsIconImageGeneratorView: View {
         isGenerating = true
 
         // Generate on background thread to avoid UI freeze
-        DispatchQueue.global(qos: .userInitiated).async {
-            let image = SportsIconImageGenerator.generateImage()
+        Task {
+            let image = await Task.detached(priority: .userInitiated) {
+                SportsIconImageGenerator.generateImage()
+            }.value
 
-            DispatchQueue.main.async {
-                withAnimation {
-                    generatedImage = image
-                    isGenerating = false
-                }
+            withAnimation {
+                generatedImage = image
+                isGenerating = false
             }
         }
     }