Mail Template Multi Company

This module extends the standard email templates in Odoo so that each template can be linked to a company.

• On the email template form, a new Company field appears right after the Model field. It is only visible to users who have access to multiple companies.
• The same Company column is added to the email template list view, and a Company filter is added to the search view, so users can find templates by company.
• A record rule named "Mail Template multi-company" restricts which templates each user can see: templates with no company (shared) plus templates belonging to the companies currently selected for that user.
• The Company field can be left empty, meaning the template is shared across companies. If a company is deleted, the link is cleared automatically instead of deleting the template.

The module touches the mail.template model and the standard email template screens (form, list and search views). It does not add new menus or buttons; it only enriches the existing email template configuration area with company information and access rules.