feat(push): send silent iOS wakeups via FCM APNs background

Use apns-push-type background, priority 5, contentAvailable-only aps
payload, and WAKEUP_PING data without alert or sound.

src/services/pushService.ts

@@ -41,9 +41,26 @@ export async function sendPushToDevice(
   }
 
   try {
+    const device = { fcmToken };
+    const data: Record<string, string> = {
+      ...stringifyData(payload),
+      type: "WAKEUP_PING",
+    };
+
     await messaging.send({
-      token: fcmToken,
-      data: stringifyData(payload),
+      token: device.fcmToken,
+      apns: {
+        headers: {
+          "apns-push-type": "background",
+          "apns-priority": "5",
+        },
+        payload: {
+          aps: {
+            contentAvailable: true,
+          },
+        },
+      },
+      data,
     });
     await db.setLastNotifiedAt(fcmToken, new Date());
     return "sent";