fix(web): fetch templates on dialog open via layout composable (#1837) (#1839)

fix(web): fetch templates on dialog open via layout composable (#1837) (#1839)

Expose getTemplates from useLayoutData instead of duplicating the fetch
in useAddStationsForm. Each layout triggers the refresh at the right
moment:

- Modern skin: watch showAddDialog → getTemplates() on open
- Classic skin: watch route → getTemplates() on ADD_CHARGING_STATIONS

The templatesEqual guard in useAddStationsForm prevents resetting the
user's selection when the refetch returns an identical list.

Co-authored-by: Jérôme Benoit <jerome.benoit@sap.com>