fix: restore only main macOS window and select active downloads

ui/flutter/docs/window-capability-rpc.md

@@ -85,6 +85,12 @@ Appearance synchronization uses `appearance.changed` and currently contains:
 - Theme color
 - Locale
 
+After successful task creation, a child calls the typed
+`NavigationMethods.showDownloadingTasks` capability before closing. The host
+routes to the task list and resets its filter to downloading, including any
+search or selection on an already-mounted list. This does not show or focus a
+hidden main window. Cancellation and failed creation do not request navigation.
+
 State broadcasting must observe the owning Riverpod state centrally. Do not broadcast directly from a settings button callback, because updates can originate from configuration loading, system changes, or future entry points.
 
 ## 6. Storage