Add one-click Update All with batch progress dialog

New batch_update_dialog shows all updatable AppImages with per-app
status badges and overall progress bar. Wired as win.update-all action
from dashboard when updates are available.

src/window.rs

@@ -666,6 +666,17 @@ impl DriftwoodWindow {
         }
         self.add_action(&batch_delete_action);
 
+        let update_all_action = gio::SimpleAction::new("update-all", None);
+        {
+            let window_weak = self.downgrade();
+            update_all_action.connect_activate(move |_, _| {
+                let Some(window) = window_weak.upgrade() else { return };
+                let db = window.database();
+                crate::ui::batch_update_dialog::show_batch_update_dialog(&window, db);
+            });
+        }
+        self.add_action(&update_all_action);
+
         // --- Context menu actions (parameterized with record ID) ---
         let param_type = Some(glib::VariantTy::INT64);