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/Export/Services/RemoteImageService.swift

@@ -7,6 +7,7 @@
 
 import Foundation
 import UIKit
+import LRUCache
 
 actor RemoteImageService {
 
@@ -32,7 +33,7 @@ actor RemoteImageService {
     // MARK: - Properties
 
     private let urlSession: URLSession
-    private var imageCache: [URL: UIImage] = [:]
+    private let imageCache = LRUCache<URL, UIImage>(countLimit: 50)
 
     // MARK: - Init
 
@@ -56,7 +57,7 @@ actor RemoteImageService {
     /// Fetch a single image from URL
     func fetchImage(from url: URL) async throws -> UIImage {
         // Check cache first
-        if let cached = imageCache[url] {
+        if let cached = imageCache.value(forKey: url) {
             return cached
         }
 
@@ -79,7 +80,7 @@ actor RemoteImageService {
         let scaledImage = scaleImage(image, maxWidth: 400)
 
         // Cache it
-        imageCache[url] = scaledImage
+        imageCache.setValue(scaledImage, forKey: url)
 
         return scaledImage
     }