Fix Qwen3-TTS gradio demo

[noobHappylife]

Purpose

The Qwen3-TTS is not working as-is now. 2 issues:

• page-init JS path doesn't seem to be registered properly, so window.ttsGenerate was never registered and the browser never sent the speech request.
• for CustomVoice task, it's using "speaker" param field, which has no impact.

Fixed the page-init JS path so it registered properly, and change the "speaker" param field to "voice"

Test Plan

Test Result

Tested it locally and the CustomVoice demo is working with different speaker.

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[princepride]

LGTM