chore: Migrate mailers from the worker to jobs (#12331)

Previously, email replies were handled inside workers. There was no
execution logs. This meant if emails silently failed (as reported by a
customer), we had no way to trace where the issue happened, the only
assumption was “no error = mail sent.”

By moving email handling into jobs, we now have proper execution logs
for each attempt. This makes it easier to debug delivery issues and
would have better visibility when investigating customer reports.

Fixes
https://linear.app/chatwoot/issue/CW-5538/emails-are-not-sentdelivered-to-the-contact

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>
Co-authored-by: Shivam Mishra <scm.mymail@gmail.com>

app/models/message.rb

@@ -300,7 +300,6 @@ class Message < ApplicationRecord
   def execute_after_create_commit_callbacks
     # rails issue with order of active record callbacks being executed https://github.com/rails/rails/issues/20911
     reopen_conversation
-    notify_via_mail
     set_conversation_activity
     dispatch_create_events
     send_reply
@@ -386,48 +385,6 @@ class Message < ApplicationRecord
     ::MessageTemplates::HookExecutionService.new(message: self).perform
   end
 
-  def email_notifiable_webwidget?
-    inbox.web_widget? && inbox.channel.continuity_via_email
-  end
-
-  def email_notifiable_api_channel?
-    inbox.api? && inbox.account.feature_enabled?('email_continuity_on_api_channel')
-  end
-
-  def email_notifiable_channel?
-    email_notifiable_webwidget? || %w[Email].include?(inbox.inbox_type) || email_notifiable_api_channel?
-  end
-
-  def can_notify_via_mail?
-    return unless email_notifiable_message?
-    return unless email_notifiable_channel?
-    return if conversation.contact.email.blank?
-
-    true
-  end
-
-  def notify_via_mail
-    return unless can_notify_via_mail?
-
-    trigger_notify_via_mail
-  end
-
-  def trigger_notify_via_mail
-    return EmailReplyWorker.perform_in(1.second, id) if inbox.inbox_type == 'Email'
-
-    # will set a redis key for the conversation so that we don't need to send email for every new message
-    # last few messages coupled together is sent every 2 minutes rather than one email for each message
-    # if redis key exists there is an unprocessed job that will take care of delivering the email
-    return if Redis::Alfred.get(conversation_mail_key).present?
-
-    Redis::Alfred.setex(conversation_mail_key, id)
-    ConversationReplyEmailWorker.perform_in(2.minutes, conversation.id, id)
-  end
-
-  def conversation_mail_key
-    format(::Redis::Alfred::CONVERSATION_MAILER_KEY, conversation_id: conversation.id)
-  end
-
   def validate_attachments_limit(_attachment)
     errors.add(:attachments, message: 'exceeded maximum allowed') if attachments.size >= NUMBER_OF_PERMITTED_ATTACHMENTS
   end