fix: Preserve original filenames for WhatsApp cloud attachments (#14168)

## Summary

Preserves the original filename provided in the WhatsApp Cloud
attachment payload when downloading media files.

## Problem

Files containing accented or special characters could be saved with
malformed names or incorrect extensions due to relying on remote
download metadata.

## Changes Made

- Uses attachment_payload[:filename] when present
- Creates a tempfile using the original filename and extension
- Preserves content type metadata
- Falls back to existing behavior when no filename is provided

## Notes

This should improve attachment downloads for filenames containing
accented characters.
Related to #10973

---------

Co-authored-by: Rorrick Smith <rorrick@bulksms.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: Muhsin <12408980+muhsin-k@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

app/services/whatsapp/incoming_message_whatsapp_cloud_service.rb

@@ -13,8 +13,17 @@ class Whatsapp::IncomingMessageWhatsappCloudService < Whatsapp::IncomingMessageB
       inbox.channel.media_url(attachment_payload[:id]),
       headers: inbox.channel.api_headers
     )
+
     # This url response will be failure if the access token has expired.
     inbox.channel.authorization_error! if url_response.unauthorized?
-    Down.download(url_response.parsed_response['url'], headers: inbox.channel.api_headers) if url_response.success?
+
+    return unless url_response.success?
+
+    downloaded_file = Down.download(url_response.parsed_response['url'], headers: inbox.channel.api_headers)
+    # WhatsApp Cloud sends the original filename in the payload; preserve it so accented
+    # names keep their correct extension instead of relying on the mangled remote metadata.
+    filename = attachment_payload[:filename]
+    downloaded_file.define_singleton_method(:original_filename) { filename } if filename.present?
+    downloaded_file
   end
 end

spec/services/whatsapp/incoming_message_whatsapp_cloud_service_spec.rb

@@ -59,6 +59,41 @@ describe Whatsapp::IncomingMessageWhatsappCloudService do
       end
     end
 
+    context 'when document attachment includes an accented filename' do
+      let(:document_params) do
+        {
+          phone_number: whatsapp_channel.phone_number,
+          object: 'whatsapp_business_account',
+          entry: [{
+            changes: [{
+              value: {
+                contacts: [{ profile: { name: 'Sojan Jose' }, wa_id: '2423423243' }],
+                messages: [{
+                  from: '2423423243',
+                  document: {
+                    id: 'b1c68f38-8734-4ad3-b4a1-ef0c10d683',
+                    mime_type: 'application/pdf',
+                    filename: 'Currículum café.pdf',
+                    caption: 'My résumé'
+                  },
+                  timestamp: '1664799904', type: 'document'
+                }]
+              }
+            }]
+          }]
+        }.with_indifferent_access
+      end
+
+      it 'preserves the original filename from the payload' do
+        stub_media_url_request
+        stub_sample_png_request
+        described_class.new(inbox: whatsapp_channel.inbox, params: document_params).perform
+
+        attachment = whatsapp_channel.inbox.messages.first.attachments.first
+        expect(attachment.file.filename.to_s).to eq('Currículum café.pdf')
+      end
+    end
+
     context 'when invalid attachment message params' do
       let(:error_params) do
         {