fix(types): resolve all TypeScript compilation errors from non-null assertion removal

Fixes:
- chats.ts: revert encodeResult/initial to ! (guaranteed by callback assignment)
- groups.ts: fix operator precedence with ?? (wrap +attrs in parens), fix groupId type
- messages-recv.ts: extract messageKey.id to local const with fallback
- socket.ts: revert onClose! (guaranteed by synchronous callback assignment)
- event-buffer.ts: add 'notify' fallback for MessageUpsertType
- messages.ts: add filePath const after null guard, fix contextInfo type assertion
- noise-handler.ts: restore array index ! (guaranteed by length check)

Build now compiles with zero new errors.

https://claude.ai/code/session_01E2cfX1N3sJgCJBTvzGazSG

src/Utils/event-buffer.ts

@@ -1265,7 +1265,7 @@ function consolidateEvents(data: BufferedEventData) {
 
 	const messageUpsertList = Object.values(data.messageUpserts)
 	if (messageUpsertList.length) {
-		const type = messageUpsertList[0]?.type
+		const type = messageUpsertList[0]?.type ?? 'notify'
 		map['messages.upsert'] = {
 			messages: messageUpsertList.map(m => m.message),
 			type

src/Utils/messages.ts

@@ -264,9 +264,11 @@ export const prepareWAMessageMedia = async (
 					throw new Boom('Missing file path for processing')
 				}
 
+				const filePath = originalFilePath!
+
 				if (requiresThumbnailComputation) {
 					const { thumbnail, originalImageDimensions } = await generateThumbnail(
-						originalFilePath,
+						filePath,
 						mediaType as 'image' | 'video',
 						options
 					)
@@ -281,12 +283,12 @@ export const prepareWAMessageMedia = async (
 				}
 
 				if (requiresDurationComputation) {
-					uploadData.seconds = await getAudioDuration(originalFilePath)
+					uploadData.seconds = await getAudioDuration(filePath)
 					logger?.debug('computed audio duration')
 				}
 
 				if (requiresWaveformProcessing) {
-					uploadData.waveform = await getAudioWaveform(originalFilePath, logger)
+					uploadData.waveform = await getAudioWaveform(filePath, logger)
 					logger?.debug('processed waveform')
 				}
 
@@ -1767,7 +1769,7 @@ export const generateWAMessageFromContent = (
 
 		const innerContent = innerMessage[key as Exclude<keyof proto.IMessage, 'conversation'>]
 		const contextInfo: proto.IContextInfo =
-			(innerContent && 'contextInfo' in innerContent && innerMessage[key as Exclude<keyof proto.IMessage, 'conversation'>]?.contextInfo) || {}
+			(innerContent && typeof innerContent === 'object' && 'contextInfo' in innerContent && (innerContent as Record<string, unknown>).contextInfo as proto.IContextInfo) || {}
 		contextInfo.participant = jidNormalizedUser(participant ?? '')
 		contextInfo.stanzaId = quoted.key.id
 		contextInfo.quotedMessage = quotedMsg

src/Utils/noise-handler.ts

@@ -150,7 +150,7 @@ export const makeNoiseHandler = ({
 		while (true) {
 			if (inBytes.length < 3) return
 
-			size = (inBytes[0] << 16) | (inBytes[1] << 8) | inBytes[2]
+			size = (inBytes[0]! << 16) | (inBytes[1]! << 8) | inBytes[2]!
 
 			if (inBytes.length < size + 3) return