Add PWA, service worker and Web Push

- Use new notification request/opt-in flow for push
- Implement unsubscribing
- Implement muting
- Implement emojis in title
- Add iOS specific PWA warning
- Don’t use websockets when web push is enabled
- Fix duplicate notifications
- Implement default web push setting
- Implement changing subscription type
- Implement web push subscription refresh
- Implement web push notification click

web/src/app/db.js

@@ -1,21 +0,0 @@
-import Dexie from "dexie";
-import session from "./Session";
-
-// Uses Dexie.js
-// https://dexie.org/docs/API-Reference#quick-reference
-//
-// Notes:
-// - As per docs, we only declare the indexable columns, not all columns
-
-// The IndexedDB database name is based on the logged-in user
-const dbName = session.username() ? `ntfy-${session.username()}` : "ntfy";
-const db = new Dexie(dbName);
-
-db.version(1).stores({
-  subscriptions: "&id,baseUrl",
-  notifications: "&id,subscriptionId,time,new,[subscriptionId+new]", // compound key for query performance
-  users: "&baseUrl,username",
-  prefs: "&key",
-});
-
-export default db;