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/test/kotlin/com/subtracks/ui/components/ContextMenuHostTest.kt

@@ -0,0 +1,19 @@
+package com.subtracks.ui.components
+
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.test.runTest
+import kotlinx.coroutines.withTimeoutOrNull
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class ContextMenuHostTest {
+    @Test
+    fun aDismissalBeforeCollectionIsStillDelivered() =
+        runTest {
+            val host = ContextMenuHost()
+
+            host.dismissTransients()
+
+            assertEquals(Unit, withTimeoutOrNull(1_000) { host.dismissals.first() })
+        }
+}