fix: rename logoff to logout

keeps naming more consistent

src/Client.js

@@ -100,7 +100,7 @@ export class Client extends EventEmitter {
         }
     }
 
-    logoff() {
+    logout() {
         if (!this.#ws || this.#ws.readyState !== WebSocket.OPEN) {
             throw new Error('not connected')
         }