feat: automate account deletion (#11406)

- Automate the deletion of accounts that have requested deletion via
account settings.
- Add a Sidekiq job that runs daily to find accounts that have requested
deletion and have passed the 7-day window.
- This job deletes the account and then soft-deletes users if they do
not belong to any other account.
- This job also sends an email to the Chatwoot instance admin for
compliance purposes.
- The Chatwoot instance admin's email is configurable via the
`CHATWOOT_INSTANCE_ADMIN_EMAIL` global config.

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/mailers/administrator_notifications/account_compliance_mailer.rb

@@ -0,0 +1,53 @@
+class AdministratorNotifications::AccountComplianceMailer < AdministratorNotifications::BaseMailer
+  def account_deleted(account)
+    return if instance_admin_email.blank?
+
+    subject = subject_for(account)
+    meta = build_meta(account)
+
+    send_notification(subject, to: instance_admin_email, meta: meta)
+  end
+
+  private
+
+  def build_meta(account)
+    deleted_users = params[:soft_deleted_users] || []
+
+    user_info_list = []
+    deleted_users.each do |user|
+      user_info_list << {
+        'user_id' => user[:id].to_s,
+        'user_email' => user[:original_email].to_s
+      }
+    end
+
+    {
+      'instance_url' => instance_url,
+      'account_id' => account.id,
+      'account_name' => account.name,
+      'deleted_at' => format_time(Time.current.iso8601),
+      'deletion_reason' => account.custom_attributes['marked_for_deletion_reason'] || 'not specified',
+      'marked_for_deletion_at' => format_time(account.custom_attributes['marked_for_deletion_at']),
+      'soft_deleted_users' => user_info_list,
+      'deleted_user_count' => user_info_list.size
+    }
+  end
+
+  def format_time(time_string)
+    return 'not specified' if time_string.blank?
+
+    Time.zone.parse(time_string).strftime('%B %d, %Y %H:%M:%S %Z')
+  end
+
+  def subject_for(account)
+    "Account Deletion Notice for #{account.id} - #{account.name}"
+  end
+
+  def instance_admin_email
+    GlobalConfig.get('CHATWOOT_INSTANCE_ADMIN_EMAIL')['CHATWOOT_INSTANCE_ADMIN_EMAIL']
+  end
+
+  def instance_url
+    ENV.fetch('FRONTEND_URL', 'not available')
+  end
+end