List of steps to reproduce (step by step, including full links if applicable):

• If you have a wiki with the MediaSearch and WikibaseMediaInfo extensions installed (e.g. commons) then, for non-logged-in users or users without the 'sdms-special-search' preference set, the sidebar search form contains a 'title' field with the value 'Special:Mediasearch'
• in modern vector the search form is replaced with a Vue form when the user clicks into it, but with a different value for the 'title' field

What happens?:

• ... which means all users get Special:Search instead of MediaSearch

What needs to be done?

• Vector/resources/skin.vector.search/App.vue needs to use Skin.php::getSearchPageTitle() for the value of the hidden title field instead of a hardcoded value