address review: replay one dismissal so a recreated screen still sees it

A notification tap can fire the dismissal before the route's collector
subscribes (activity recreated with a restored options sheet), and a
replay-zero broadcast drops it. Replaying one is a no-op on default state
and the new ContextMenuHost test guards it.

app/src/main/kotlin/com/subtracks/ui/components/ItemContextMenu.kt

@@ -151,7 +151,9 @@ class ContextMenuHost {
     var actions by mutableStateOf(ItemActions())
         private set
 
-    private val transientDismissals = MutableSharedFlow<Unit>(extraBufferCapacity = 1)
+    // Replay one so a screen recreated by the notification (whose collector subscribes after the
+    // event fires) still sees the dismissal; every onDismiss is a harmless no-op on default state.
+    private val transientDismissals = MutableSharedFlow<Unit>(replay = 1)
 
     // Fires when an external event (opening now playing) should close menu-like UI the host does
     // not own, such as the library's list options sheet.

app/src/main/kotlin/com/subtracks/ui/library/LibraryScreen.kt

@@ -420,6 +420,7 @@ fun LibraryScreen(
     var searchActive by rememberSaveable { mutableStateOf(false) }
     val searchFocus = remember { FocusRequester() }
 
+    // Search mode is left open so the typed query survives; MainNavigation dismisses the keyboard.
     DismissOnRequest(dismissals) { showOptions = false }
 
     LaunchedEffect(pagerState) {