## Description Implement functionality for adding artworks to existing galleries. Users can already create galleries from the profile page, but artworks cannot currently be added to them. The add button on the artwork detail page should allow the user to choose one of their galleries and save the selected artwork there. ## Done when - [x] Users can add artwork to one of their existing galleries - [x] The add button opens a gallery selection interface - [x] The selected artwork is stored persistently in the database - [x] Added artworks are shown inside the corresponding gallery - [x] The functionality works after refresh and login