Asks the user to attach a folder of THEIR OWN source footage to the project — opens a dialog in Frapea with a 'Connect folder' button. Only a human can do this (browser security gesture): tell the user IN YOUR REPLY to click it, then call await_user_action with the returned actionId; on 'granted', get_media will list the folder's files. Use when get_media comes back empty and the user has footage somewhere on their disk. NEVER call it for files YOU made or fetched. The project folder's media/ folder is scanned: any media file placed there joins the pool by itself (within a second, or when the user returns to the tab), with no dialog. reason is shown in the dialog word for word — say which footage you need and what you will do with it, so the user knows what to pick.