feat: collab hocuspocus v4 upgrade (#2351)

* WIP 1

* complete v4 migration

* add flushDelay

* feat: multiplexing

* fix: survive hocuspocus v4 message timeout

* fix: searchTerm type error

apps/server/src/collaboration/extensions/redis-sync/ws-socket-wrapper.ts

@@ -1,20 +1,17 @@
-import { EventEmitter } from 'events';
 import type WebSocket from 'ws';
+import type { WebSocketLike } from '@hocuspocus/server';
 
 /**
- * Wrapper around ws WebSocket that only receives events via emit().
- * This prevents double-handling when used with RedisSyncExtension.
+ * Wrapper around ws WebSocket that Hocuspocus only writes to.
+ * Incoming socket events are forwarded separately by the gateway,
+ * which prevents double-handling with RedisSyncExtension.
  */
-export class WsSocketWrapper extends EventEmitter {
+export class WsSocketWrapper implements WebSocketLike {
   private ws: WebSocket;
   readyState = 1;
 
   constructor(ws: WebSocket) {
-    super();
     this.ws = ws;
-    this.once('close', () => {
-      this.readyState = 3;
-    });
   }
 
   close(code?: number, reason?: string) {
@@ -27,15 +24,6 @@ export class WsSocketWrapper extends EventEmitter {
     }
   }
 
-  ping() {
-    if (this.readyState !== 1) return;
-    try {
-      this.ws.ping();
-    } catch (e) {
-      // Socket already closed
-    }
-  }
-
   send(message: Uint8Array) {
     if (this.readyState !== 1) return;
     try {