Fix: Forzar mimetype ogg para notas de voz PTT

- Preferir grabacion en ogg/opus en el navegador
- Forzar mimetype a audio/ogg; codecs=opus para PTT en servidor
- WhatsApp requiere ogg para notas de voz

server/api/messages/[instanceId]/[chatId]/send.post.ts

@@ -274,10 +274,19 @@ async function handleMediaMessage(
             mimetype: file.type
           } as AnyMediaMessageContent
         } else if (mediaType === 'audio') {
+          // For PTT (voice notes), WhatsApp requires audio/ogg; codecs=opus
+          // If the browser sends webm, we force the mimetype to ogg
+          // The opus codec is the same, just different container
+          let audioMimetype = file.type
+          if (isPtt && file.type.includes('webm')) {
+            audioMimetype = 'audio/ogg; codecs=opus'
+            console.log(`[Send] Converting PTT mimetype from ${file.type} to ${audioMimetype}`)
+          }
+
           content = {
             audio: file.data,
             ptt: isPtt,
-            mimetype: file.type
+            mimetype: audioMimetype
           } as AnyMediaMessageContent
         } else {
           // Document