Feat: restore the "backend: 'WebAudio'" option

[katspaugh]

Short description

Resolves #3272

I've restored the backend: 'WebAudio' option.

Implementation details

There's a new class WebAudioPlayer that can be used as a drop-in replacement for a HTMLMediaElement. It emulates an audio element via a Web Audio buffer source node.

Checklist

• This PR is covered by e2e tests
• It introduces no breaking API changes

[github-actions]

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Type	Occurrences	Fixable
Errors	0	0
Warnings	0	0
Ignored	4	N/A

• Result: ✅ success
• Annotations: 0 total

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^{Report generated by eslint-plus-action}

[cloudflare-workers-and-pages]

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Latest commit:	4d560df
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Preview URL:	https://60b007a8.wavesurfer-js.pages.dev
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View logs

[hannahblair]

• Q: Does wavesurfer support large files?
• A: Since wavesurfer decodes audio entirely in the browser using Web Audio, large clips may fail to decode due to memory constraints. We recommend using pre-decoded peaks for large files (see this example). You can use a tool like bbc/audiowaveform to generate peaks.

I think this question in the README also needs an update. 🙂

[katspaugh]

In what sense? Nothing is changed in this regard, Web Audio has always been used for decoding. This PR is only about the playback mechanism.

[hannahblair]

In what sense? Nothing is changed in this regard, Web Audio has always been used for decoding. This PR is only about the playback mechanism.

Ah, understood. Ignore me!