feat: add background download manager with progress reporting

Co-authored-by: Cursor <cursoragent@cursor.com>

src-tauri/src/lib.rs

@@ -15,6 +15,7 @@ pub fn run() {
             dependencies::check_dependencies,
             dependencies::install_dependency,
             video::resolve_url,
+            video::start_download,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");