support aquiring server props and test dropping them

crates/chattyness-user-ui/src/api/websocket.rs

@@ -607,6 +607,20 @@ async fn handle_socket(
                                     }
                                 }
                                 ClientMessage::DropProp { inventory_item_id } => {
+                                    // Ensure instance exists for this scene (required for loose_props FK)
+                                    // In this system, channel_id = scene_id
+                                    if let Err(e) = loose_props::ensure_scene_instance(
+                                        &mut *recv_conn,
+                                        channel_id,
+                                    )
+                                    .await
+                                    {
+                                        tracing::error!(
+                                            "[WS] Failed to ensure scene instance: {:?}",
+                                            e
+                                        );
+                                    }
+
                                     // Get user's current position for random offset
                                     let member_info = channel_members::get_channel_member(
                                         &mut *recv_conn,