fix: priorizar participantAlt para sender JID en grupos

Co-authored-by: aider (openrouter/openai/gpt-5) <aider@aider.chat>

src/server.ts

@@ -233,8 +233,10 @@ export class WebhookServer {
 			return;
 		}
 
-		// Compute sender JID based on chat type
-		const senderRaw = isGroupId(remoteJid) ? participant : remoteJid;
+		// Compute sender JID based on chat type (prefer participantAlt when available due to Baileys change)
+		const senderRaw = isGroupId(remoteJid)
+			? (data.key.participantAlt || participant)
+			: remoteJid;
 
 		// Normalize sender ID for consistency and validation
 		const normalizedSenderId = normalizeWhatsAppId(senderRaw);