feat(questions): wire pruneDeadTokens into onAnswerWritten

functions/src/questions/onAnswerWritten.ts

@@ -1,6 +1,7 @@
 import * as functions from 'firebase-functions'
 import * as admin from 'firebase-admin'
 import { recipientInQuietHours } from '../notifications/quietHours'
+import { pruneDeadTokens } from '../notifications/pruneTokens'
 
 /**
  * Firestore trigger that sends an FCM notification to the other partner when
@@ -142,6 +143,8 @@ export const onAnswerWritten = functions.firestore
       console.error(`[onAnswerWritten] some notifications failed:`, failures)
     }
 
+    await pruneDeadTokens(db, partnerId, tokens, sendResults)
+
     // Track last activity time on the couple doc for re-engagement targeting.
     await db.collection('couples').doc(coupleId).update({
       lastAnsweredAt: admin.firestore.FieldValue.serverTimestamp(),