fix(types): cast axios content-type header to string

AxiosHeaderValue widened to include number; explicit String() cast keeps
runtime behavior and unblocks tsc --noEmit.

Author: DavidsonGomes

src/api/integrations/channel/whatsapp/whatsapp.baileys.service.ts

@@ -3107,7 +3107,7 @@ export class BaileysStartupService extends ChannelStartupService {
 
           const response = await axios.get(mediaMessage.media, config);
 
-          mimetype = response.headers['content-type'];
+          mimetype = String(response.headers['content-type']);
         }
       }
 

src/api/integrations/chatbot/chatwoot/services/chatwoot.service.ts

@@ -1252,7 +1252,7 @@ export class ChatwootService {
         const response = await axios.get(media, {
           responseType: 'arraybuffer',
         });
-        mimeType = response.headers['content-type'];
+        mimeType = String(response.headers['content-type']);
       }
 
       let type = 'document';
@@ -2402,7 +2402,7 @@ export class ChatwootService {
         if (isAdsMessage) {
           const imgBuffer = await axios.get(adsMessage.thumbnailUrl, { responseType: 'arraybuffer' });
 
-          const extension = mimeTypes.extension(imgBuffer.headers['content-type']);
+          const extension = mimeTypes.extension(String(imgBuffer.headers['content-type']));
           const mimeType = extension && mimeTypes.lookup(extension);
 
           if (!mimeType) {