fix: 14 audit fixes — concurrency, memory, performance, accessibility

Second audit round addressing data races, task stacking, unbounded
caches, and VoiceOver gaps across 7 files.

Concurrency:
- Move NSItemProvider @State access into MainActor block (3 drop handlers)
- Cancel stale ScheduleViewModel tasks on rapid filter changes

Memory:
- Replace unbounded image dict with LRUCache(countLimit: 50)
- Replace demo-mode asyncAfter with cancellable Task

Performance:
- Wrap debug NBA print() in #if DEBUG
- Cache visitsById via @State + onChange instead of per-render computed
- Pre-compute sportProgressFractions in ProgressViewModel
- Replace allGames computed property with hasGames bool check
- Cache sortedTrips via @State + onChange in SavedTripsListView

Accessibility:
- Add combined VoiceOver label to progress ring
- Combine away/home team text into single readable phrase
- Hide decorative StadiumDetailSheet icon from VoiceOver
- Add explicit accessibilityLabel to SportFilterChip
- Add combined accessibilityLabel to GameRowView

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

SportsTime/Features/Schedule/ViewModels/ScheduleViewModel.swift

@@ -28,6 +28,7 @@ final class ScheduleViewModel {
     private(set) var errorMessage: String?
 
     private let dataProvider = AppDataProvider.shared
+    private var loadTask: Task<Void, Never>?
 
     // MARK: - Pre-computed Groupings (avoid computed property overhead)
 
@@ -117,6 +118,7 @@ final class ScheduleViewModel {
                 logger.info("📅   \(sport.rawValue): \(count) games")
             }
 
+            #if DEBUG
             // Debug: Print all NBA games
             let nbaGames = games.filter { $0.game.sport == .nba }
             print("🏀 [DEBUG] All NBA games in schedule (\(nbaGames.count) total):")
@@ -124,6 +126,7 @@ final class ScheduleViewModel {
                 let dateStr = game.game.dateTime.gameDateTimeString(in: game.stadium.timeZone)
                 print("🏀   \(dateStr): \(game.awayTeam.name) @ \(game.homeTeam.name) (\(game.game.id))")
             }
+            #endif
 
         } catch let cloudKitError as CloudKitError {
             self.error = cloudKitError
@@ -151,9 +154,8 @@ final class ScheduleViewModel {
             selectedSports.insert(sport)
         }
         AnalyticsManager.shared.track(.scheduleFiltered(sport: sport.rawValue, dateRange: "\(startDate.formatted(.dateTime.month().day())) - \(endDate.formatted(.dateTime.month().day()))"))
-        Task {
-            await loadGames()
-        }
+        loadTask?.cancel()
+        loadTask = Task { await loadGames() }
     }
 
     func resetFilters() {
@@ -161,17 +163,15 @@ final class ScheduleViewModel {
         searchText = ""
         startDate = Date()
         endDate = Calendar.current.date(byAdding: .day, value: 14, to: Date()) ?? Date()
-        Task {
-            await loadGames()
-        }
+        loadTask?.cancel()
+        loadTask = Task { await loadGames() }
     }
 
     func updateDateRange(start: Date, end: Date) {
         startDate = start
         endDate = end
-        Task {
-            await loadGames()
-        }
+        loadTask?.cancel()
+        loadTask = Task { await loadGames() }
     }
 
     // MARK: - Filtering & Grouping (pre-computed, not computed properties)