fix: poster WS remote control - push open and resolve file obj

- launcher_file_cont: poster 'Open Poster' click now sends ae_open:event_file
  command to remote display when controller=local_push and WS is connected
- +layout.svelte handle_ws_recv: ae_open: handler now looks up the file obj
  from Dexie after setting modal__open_event_file_id, so the remote modal
  has the hosted_file_id needed to render the poster image (was showing
  'No image selected' on remote device)

src/routes/events/[event_id]/(launcher)/launcher/+layout.svelte

@@ -340,6 +340,14 @@
                     restartCountdown();
                     $events_slct.event_file_id = obj_id;
                     $events_sess.launcher.modal__open_event_file_id = obj_id;
+                    // Look up the file object from Dexie so the modal can render the image.
+                    // The remote device has no event_file_obj in scope — only the ID was sent over WS.
+                    db_events.file.get(obj_id).then((file_obj: any) => {
+                        if (file_obj) {
+                            $events_sess.launcher.modal__event_file_obj = file_obj;
+                            $events_sess.launcher.modal__title = file_obj.filename ?? '';
+                        }
+                    });
                 }
             } else if (cmd.startsWith('ae_close:')) {
                 if (cmd.split(':')[1] == 'event_file_modal') {