📝 docs(agora-stt): update button text in e2e test page

- 修改"加入频道"按钮文本为"加入语音频道"以更准确反映功能

tests/e2e/pages/admin/agora-stt.page.ts

@@ -20,7 +20,7 @@ export class AgoraSTTPage {
   constructor(page: Page) {
     this.page = page;
     this.pageTitle = page.getByRole('heading', { name: '语音转文字' });
-    this.joinChannelButton = page.getByRole('button', { name: /加入频道|连接中\.\.\./ });
+    this.joinChannelButton = page.getByRole('button', { name: /加入语音频道|连接中\.\.\./ });
     this.leaveChannelButton = page.getByRole('button', { name: '离开频道' });
     this.startRecordingButton = page.getByRole('button', { name: '开始录音' });
     this.stopRecordingButton = page.getByRole('button', { name: '停止录音' });