fix: Dynamic Island, Live Activity errors, background audio stop, CFBundleVersion

Phase 1 — Audio background resilience:
- Remove .mixWithOthers, app takes audio focus for coach cues
- Add AVAudioSession.interruptionNotification handler (re-activates after calls/Siri)
- Add AVAudioSession.routeChangeNotification handler (re-activates on headphone changes)

Phase 2 — Live Activity error surfacing:
- PlayerViewModel: @Published liveActivityError captures auth-denied + request errors
- PlayerView: translucent error banner with dismiss button (non-blocking)

Phase 3 — CFBundleVersion 1→2 in all 4 Info.plist files (match project.yml CURRENT_PROJECT_VERSION: 2)

tabatago-swift/TabataGo/Services/AudioService.swift

@@ -28,12 +28,55 @@ final class AudioService {
             try audioSession.setCategory(
                 .playback,
                 mode: .default,
-                options: [.mixWithOthers, .allowAirPlay, .allowBluetooth]
+                options: [.allowAirPlay, .allowBluetooth]
             )
             try audioSession.setActive(true)
         } catch {
             print("[Audio] Session configuration failed: \(error)")
         }
+
+        // ─── Interruption Handler
+        NotificationCenter.default.addObserver(
+            forName: AVAudioSession.interruptionNotification,
+            object: nil,
+            queue: .main
+        ) { [weak self] notification in
+            guard let self,
+                  let typeValue = notification.userInfo?[AVAudioSessionInterruptionTypeKey] as? UInt,
+                  let type = AVAudioSession.InterruptionType(rawValue: typeValue) else { return }
+
+            if type == .ended {
+                guard let optionsValue = notification.userInfo?[AVAudioSessionInterruptionOptionKey] as? UInt,
+                      AVAudioSession.InterruptionOptions(rawValue: optionsValue).contains(.shouldResume) else { return }
+                do {
+                    try self.audioSession.setActive(true)
+                } catch {
+                    print("[Audio] Re-activation failed after interruption: \(error)")
+                }
+            }
+        }
+
+        // ─── Route Change Handler
+        NotificationCenter.default.addObserver(
+            forName: AVAudioSession.routeChangeNotification,
+            object: nil,
+            queue: .main
+        ) { [weak self] notification in
+            guard let self,
+                  let reasonValue = notification.userInfo?[AVAudioSessionRouteChangeReasonKey] as? UInt,
+                  let reason = AVAudioSession.RouteChangeReason(rawValue: reasonValue) else { return }
+
+            switch reason {
+            case .newDeviceAvailable, .oldDeviceUnavailable:
+                do {
+                    try self.audioSession.setActive(true)
+                } catch {
+                    print("[Audio] Route re-activation failed: \(error)")
+                }
+            default:
+                break
+            }
+        }
     }
 
     // ─── Phase Audio Cues ─────────────────────────────────────────