Root cause: CSS was setting display: flex by default which overrode
inline style="display: none" attribute on the modal element.
Solution: Changed .hvac-filter-modal default display to 'none' and
only show as 'flex' when .active or .show classes are present.
This ensures the modal respects inline styles and only appears
when explicitly activated by JavaScript.
Fixes modal overlay showing permanently on find-trainer page.
