fix(android): thread navController into inShellDetail extension

PlaylistDetailScreen takes navController for its TopAppBar back-button,
but the inShellDetail NavGraphBuilder extension was still scoped to
just expandPlayer. Added navController as the first parameter and
updated the call site.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

android/app/src/main/java/com/fabledsword/minstrel/nav/MinstrelNavGraph.kt

@@ -38,7 +38,7 @@ fun MinstrelNavGraph(
         modifier = modifier.fillMaxSize(),
     ) {
         inShellTopLevel(navController, expandPlayer)
-        inShellDetail(expandPlayer)
+        inShellDetail(navController, expandPlayer)
         outsideShell()
     }
 }
@@ -89,7 +89,10 @@ private fun NavGraphBuilder.inShellTopLevel(
     }
 }
 
-private fun NavGraphBuilder.inShellDetail(expandPlayer: () -> Unit) {
+private fun NavGraphBuilder.inShellDetail(
+    navController: NavHostController,
+    expandPlayer: () -> Unit,
+) {
     composable<AlbumDetail> { backStackEntry ->
         val route: AlbumDetail = backStackEntry.toRoute()
         ShellScaffold(onExpandPlayer = expandPlayer) {