fix: respect caller-provided waveform for PTT audio messages (#2443)

* fix: respect caller-provided waveform for PTT audio messages

When a caller explicitly passes a `waveform` in the message options,
Baileys was unconditionally overwriting it with the result of
`getAudioWaveform()`. If `audio-decode` is not installed (it is an
optional peer dependency), `getAudioWaveform()` silently returns
`undefined`, discarding the caller's value and causing WhatsApp to
render a flat-line waveform.

Fix: only invoke `getAudioWaveform()` when no waveform has been
provided by the caller (`!uploadData.waveform`).

* refactor: move waveform guard to flag definition, use typeof check

* fix: lint

Author: AshishKumarD

src/Utils/messages.ts

@@ -223,7 +223,8 @@ export const prepareWAMessageMedia = async (
 	const requiresDurationComputation = mediaType === 'audio' && typeof uploadData.seconds === 'undefined'
 	const requiresThumbnailComputation =
 		(mediaType === 'image' || mediaType === 'video') && typeof uploadData['jpegThumbnail'] === 'undefined'
-	const requiresWaveformProcessing = mediaType === 'audio' && uploadData.ptt === true
+	const requiresWaveformProcessing =
+		mediaType === 'audio' && uploadData.ptt === true && typeof uploadData.waveform === 'undefined'
 	const requiresAudioBackground = options.backgroundColor && mediaType === 'audio' && uploadData.ptt === true
 	const requiresOriginalForSomeProcessing = requiresDurationComputation || requiresThumbnailComputation
 	const { mediaKey, encFilePath, originalFilePath, fileEncSha256, fileSha256, fileLength } = await encryptedStream(