feat: Add company backfill migration for existing contacts (Part 1) (#12657)

## Description

Implements company backfill migration infrastructure for existing
contacts. This is **Part 1 of 2** for the company model production
rollout as described in
[CW-5726](https://linear.app/chatwoot/issue/CW-5726/company-model-setting-it-up-on-production).

Creates jobs and services to associate existing contacts with companies
based on their email domains, filtering out free email providers (gmail,
yahoo, etc.) and disposable addresses.
 

**What's included:**
- Business email detector service with ValidEmail2 (uses
`disposable_domain?` to avoid DNS lookups)
- Per-account batch job to process contacts for one account
- Orchestrator job to iterate all accounts
- Rake task: `bundle exec rake companies:backfill`

~~*NOTE*: I'm using a hard-coded approach to determine if something is a
"business" email by filtering out emails that are usually personal. I've
also added domains that are common to some of our customers' regions.
This should be simpler. I looked into `Valid_Email2` and I couldn't find
anything to dictate whether an email is a personal email or a business
one. I don't think the approach used in the frontend is valid here.~~
UPDATE: Using `email_provider_info` gem instead.


**Pending - Part 2 (separate PR):** Real-time company creation for new
contacts

## Type of change

- [x] New feature (non-breaking change which adds functionality)

## How Has This Been Tested?

```bash
# Run all new tests
bundle exec rspec spec/enterprise/services/companies/business_email_detector_service_spec.rb \\
                   spec/enterprise/jobs/migration/company_account_batch_job_spec.rb \\
                   spec/enterprise/jobs/migration/company_backfill_job_spec.rb

# Run RuboCop
bundle exec rubocop enterprise/app/services/companies/business_email_detector_service.rb \\
                     enterprise/app/jobs/migration/company_account_batch_job.rb \\
                     enterprise/app/jobs/migration/company_backfill_job.rb \\
                     lib/tasks/companies.rake
```

**Performance optimization:**
- Uses `disposable_domain?` instead of `disposable?` to avoid DNS MX
lookups (discovered via tcpdump analysis - `disposable?` was making
network calls for every email, causing 100x slowdown)

## Checklist:

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

---------

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

enterprise/app/jobs/migration/company_account_batch_job.rb

@@ -0,0 +1,54 @@
+class Migration::CompanyAccountBatchJob < ApplicationJob
+  queue_as :low
+
+  def perform(account)
+    account.contacts
+           .where.not(email: nil)
+           .find_in_batches(batch_size: 1000) do |contact_batch|
+      process_contact_batch(contact_batch, account)
+    end
+  end
+
+  private
+
+  def process_contact_batch(contacts, account)
+    contacts.each do |contact|
+      next unless should_process?(contact)
+
+      company = find_or_create_company(contact, account)
+      # rubocop:disable Rails/SkipsModelValidations
+      contact.update_column(:company_id, company.id) if company
+      # rubocop:enable Rails/SkipsModelValidations
+    end
+  end
+
+  def should_process?(contact)
+    return false if contact.company_id.present?
+    return false if contact.email.blank?
+
+    Companies::BusinessEmailDetectorService.new(contact.email).perform
+  end
+
+  def find_or_create_company(contact, account)
+    domain = extract_domain(contact.email)
+    company_name = derive_company_name(contact, domain)
+
+    Company.find_or_create_by!(account: account, domain: domain) do |company|
+      company.name = company_name
+    end
+  rescue ActiveRecord::RecordNotUnique
+    # Race condition: Another job created it between our check and create
+    # just find the one that was created
+
+    Company.find_by(account: account, domain: domain)
+  end
+
+  def extract_domain(email)
+    email.split('@').last&.downcase
+  end
+
+  def derive_company_name(contact, domain)
+    contact.additional_attributes&.dig('company_name').presence ||
+      domain.split('.').first.tr('-_', ' ').titleize
+  end
+end

enterprise/app/jobs/migration/company_backfill_job.rb

@@ -0,0 +1,17 @@
+class Migration::CompanyBackfillJob < ApplicationJob
+  queue_as :low
+
+  def perform
+    Rails.logger.info 'Starting company backfill migration...'
+    account_count = 0
+    Account.find_in_batches(batch_size: 100) do |accounts|
+      accounts.each do |account|
+        Rails.logger.info "Enqueuing company backfill for account #{account.id}"
+        Migration::CompanyAccountBatchJob.perform_later(account)
+        account_count += 1
+      end
+    end
+
+    Rails.logger.info "Company backfill migration complete. Enqueued jobs for #{account_count} accounts."
+  end
+end

enterprise/app/models/company.rb

@@ -12,9 +12,9 @@
 #
 # Indexes
 #
-#  index_companies_on_account_id             (account_id)
-#  index_companies_on_domain_and_account_id  (domain,account_id)
-#  index_companies_on_name_and_account_id    (name,account_id)
+#  index_companies_on_account_and_domain   (account_id,domain) UNIQUE WHERE (domain IS NOT NULL)
+#  index_companies_on_account_id           (account_id)
+#  index_companies_on_name_and_account_id  (name,account_id)
 #
 class Company < ApplicationRecord
   include Avatarable
@@ -24,6 +24,7 @@ class Company < ApplicationRecord
     with: /\A[a-zA-Z0-9]([a-zA-Z0-9-]*[a-zA-Z0-9])?(\.[a-zA-Z0-9]([a-zA-Z0-9-]*[a-zA-Z0-9])?)+\z/,
     message: I18n.t('errors.companies.domain.invalid')
   }
+  validates :domain, uniqueness: { scope: :account_id }, if: -> { domain.present? }
   validates :description, length: { maximum: Limits::COMPANY_DESCRIPTION_LENGTH_LIMIT }
 
   belongs_to :account

enterprise/app/services/companies/business_email_detector_service.rb

@@ -0,0 +1,19 @@
+class Companies::BusinessEmailDetectorService
+  attr_reader :email
+
+  def initialize(email)
+    @email = email
+  end
+
+  def perform
+    return false if email.blank?
+
+    address = ValidEmail2::Address.new(email)
+    return false unless address.valid?
+    return false if address.disposable_domain?
+
+    provider = EmailProviderInfo.call(email)
+
+    provider.nil?
+  end
+end