Maintenance Equipment Categories always_fold is indicate it

This module extends the Maintenance app's Equipment Categories. On the category form, a new checkbox called "Always Folded in Maintenance Pipe" appears right after the Technician field.

• When the checkbox is ticked, the category is automatically kept folded (collapsed) in the maintenance pipeline/kanban view, so its equipment cards are hidden until the user expands it.
• When the checkbox is not ticked, the category behaves exactly as before, following Odoo's normal folding rules.
• The folding is recalculated automatically whenever the category's equipment list or the checkbox value changes, so the setting stays applied without manual action.

The change touches the maintenance.equipment.category model and its form view. No new menus, reports, emails or scheduled jobs are added. A demo category named "AF Category" with the option enabled, plus an equipment record linked to it, is included for testing purposes.