ActivityKit push notifications

Live Activity updates are APNs pushes, but they are not the same as alert notifications. Apple requires:

• Header apns-push-type: liveactivity
• Topic {bundleId}.push-type.liveactivity
• Body with aps.event of update or end, plus aps.content-state
• A device token issued for that Live Activity, not the app’s generic push token

FCM and generic “send notification” SDKs often cannot set this push type. If you try, Apple rejects the request. See Live Activity push tokens and the APNs docs.