Default web push to enabled on PWAs

web/src/app/Prefs.js

@@ -1,4 +1,5 @@
 import db from "./db";
+import { isLaunchedPWA } from "./utils";
 
 class Prefs {
   constructor(dbImpl) {
@@ -34,7 +35,7 @@ class Prefs {
 
   async webPushEnabled() {
     const webPushEnabled = await this.db.prefs.get("webPushEnabled");
-    return webPushEnabled?.value ?? false;
+    return webPushEnabled?.value ?? isLaunchedPWA();
   }
 
   async setWebPushEnabled(enabled) {