feat: add cron job to remove orphan conversations (#13335)

## Description

This PR includes cron job to delete the orphans

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)

## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Introduces a scheduled cleanup for conversations missing `contact` or
`inbox`.
> 
> - Adds `Internal::RemoveOrphanConversationsService` to batch-delete
orphan conversations (scoped by optional `account`, within a
configurable `days` window) with progress logging
> - New `Internal::RemoveOrphanConversationsJob` that invokes the
service; scheduled via `config/schedule.yml` to run every 12 hours on
`housekeeping` queue
> - Refactors rake task `chatwoot:ops:cleanup_orphan_conversations` to
use the service and report `total_deleted` after confirmation
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
59a24715cc59f048d08db3f588cde6fa036f3166. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------

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

lib/tasks/ops/cleanup_orphan_conversations.rake

@@ -15,13 +15,13 @@ namespace :chatwoot do
       days_input = $stdin.gets.strip
       days = days_input.empty? ? 7 : days_input.to_i
 
-      # Build a common base relation with identical joins for OR compatibility
+      service = Internal::RemoveOrphanConversationsService.new(account: account, days: days)
+
+      # Preview count using the same query logic
       base = account
              .conversations
              .where('conversations.created_at > ?', days.days.ago)
              .left_outer_joins(:contact, :inbox)
-
-      # Find conversations whose associated contact or inbox record is missing
       conversations = base.where(contacts: { id: nil }).or(base.where(inboxes: { id: nil }))
 
       count = conversations.count
@@ -31,8 +31,8 @@ namespace :chatwoot do
         print 'Do you want to delete these conversations? (y/N): '
         confirm = $stdin.gets.strip.downcase
         if %w[y yes].include?(confirm)
-          conversations.destroy_all
-          puts 'Conversations deleted.'
+          total_deleted = service.perform
+          puts "#{total_deleted} conversations deleted."
         else
           puts 'No conversations were deleted.'
         end