fix: Error shouldn't halt the campaign for entire audience (#11980)

## Summary
- handle Twilio failures per contact when running one-off SMS campaigns
- rescue errors in WhatsApp and generic SMS one-off campaigns so they
continue
- add specs confirming campaigns continue sending when a single contact
fails

fixes:  https://github.com/chatwoot/chatwoot/issues/9000

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/services/sms/oneoff_sms_campaign_service.rb

@@ -29,5 +29,7 @@ class Sms::OneoffSmsCampaignService
 
   def send_message(to:, content:)
     channel.send_text_message(to, content)
+  rescue StandardError => e
+    Rails.logger.error("[SMS Campaign #{campaign.id}] Failed to send to #{to}: #{e.message}")
   end
 end

app/services/twilio/oneoff_sms_campaign_service.rb

@@ -23,7 +23,13 @@ class Twilio::OneoffSmsCampaignService
       next if contact.phone_number.blank?
 
       content = Liquid::CampaignTemplateService.new(campaign: campaign, contact: contact).call(campaign.message)
-      channel.send_message(to: contact.phone_number, body: content)
+
+      begin
+        channel.send_message(to: contact.phone_number, body: content)
+      rescue Twilio::REST::TwilioError, Twilio::REST::RestError => e
+        Rails.logger.error("[Twilio Campaign #{campaign.id}] Failed to send to #{contact.phone_number}: #{e.message}")
+        next
+      end
     end
   end
 end

app/services/whatsapp/oneoff_campaign_service.rb

@@ -89,6 +89,7 @@ class Whatsapp::OneoffCampaignService
   rescue StandardError => e
     Rails.logger.error "Failed to send WhatsApp template message to #{to}: #{e.message}"
     Rails.logger.error "Backtrace: #{e.backtrace.first(5).join('\n')}"
-    raise e
+    # continue processing remaining contacts
+    nil
   end
 end