fix the startup reveal and the first-play hitch for real

The mini player's enter spec was decided from `firstReveal`, which was false at the first
composition (the player is not visible yet) and flipped back to `expandVertically` in the
same frame the visibility changed, so the expand animation always ran. PlaybackState now
carries `restored`, set by restore() and cleared on any user playback, and the mini
player uses it to appear in place for the whole restored session.

The first play after a restart could still pay for a fresh buffer because a stream-quality
reload rebuilds the window, and loadWindow only prepared when autoplay was set. It now
always prepares, so a reload (or the restore) leaves the current track buffered.

app/src/test/kotlin/com/subtracks/playback/PlaybackControllerTest.kt

@@ -160,6 +160,20 @@ class PlaybackControllerTest {
         assertEquals(listOf("play"), handle.operations)
     }
 
+    @Test
+    fun restoringMarksTheStateUntilPlaybackStarts() {
+        seedAlbum(5, sourceId = 1)
+        runBlocking { queues.replace(listOf(queues.albumEntry(1, "al1"))) }
+
+        controller.connect()
+        await { handle.items.isNotEmpty() }
+
+        assertTrue(controller.state.value.restored)
+
+        controller.playAlbum(1, "al1", 0)
+        await { !controller.state.value.restored }
+    }
+
     @Test
     fun nextAdvancesTheCursor() {
         seedAlbum(3, sourceId = 1)
@@ -1067,7 +1081,9 @@ class PlaybackControllerTest {
 
         assertEquals(33_000L, handle.positionMs)
         assertFalse(handle.playWhenReady)
-        assertTrue(handle.operations.drop(before).none { it.startsWith("prepare") || it.startsWith("play") })
+        val reload = handle.operations.drop(before)
+        assertTrue("a reload must re-prepare, or the next play pays for it", reload.any { it == "prepare" })
+        assertTrue(reload.none { it == "play" })
     }
 
     @Test