fix: Add missing TextEncoder to PTT

Solves this eslint issue:

/puter/packages/terminal/src/pty/PTT.js
  35:29  error  'encoder' is not defined  no-undef

Author: AtkinsSJ

packages/terminal/src/pty/PTT.js

@@ -21,6 +21,7 @@
  */
 export class PTT {
     constructor(pty) {
+        const encoder = new TextEncoder();
         this.readableStream = new ReadableStream({
             start: controller => {
                 this.readController = controller;