fix: respect caller-provided waveform for PTT audio messages (#322)

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

When sending PTT audio with an explicit waveform, Baileys unconditionally
overwrites it with getAudioWaveform() which returns undefined when
audio-decode is not installed — resulting in a flat line on WhatsApp.

Now only invokes getAudioWaveform() when no waveform is already provided,
matching the existing pattern used for jpegThumbnail (line 241).

Validated via CDP + Frida interception: WhatsApp waveform format is
64 bytes Uint8Array, values 0-99, byte-for-byte identical between
Android (audio_data table) and WA Web (model-storage IDB).

Ref: WhiskeySockets/Baileys#2443

Co-Authored-By: Renato Alcara

src/Utils/messages.ts

@@ -239,7 +239,7 @@ 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(
@@ -297,7 +297,7 @@ export const prepareWAMessageMedia = async (
 					logger?.debug('computed audio duration')
 				}
 
-				if (requiresWaveformProcessing) {
+				if (requiresWaveformProcessing && !uploadData.waveform) {
 					uploadData.waveform = await getAudioWaveform(filePath, logger)
 					logger?.debug('processed waveform')
 				}