Remove unused code and fix compiler warnings

src/state/mod.rs

@@ -39,7 +39,6 @@ pub struct AppState {
 pub struct FlattenedItem {
     pub node: FileTreeNode,
     pub depth: usize,
-    pub is_expanded: bool,
 }
 
 impl AppState {
@@ -120,20 +119,6 @@ impl AppState {
         self.flattened_items.get(self.selected_index)
     }
 
-    pub fn toggle_expand(&mut self) {
-        if let Some(item) = self.get_selected_item() {
-            if item.node.is_dir {
-                let path = item.node.path.clone();
-                if self.expanded_dirs.contains(&path) {
-                    self.expanded_dirs.remove(&path);
-                } else {
-                    self.expanded_dirs.insert(path);
-                }
-                self.rebuild_flattened_items();
-            }
-        }
-    }
-
     pub fn collapse_selected(&mut self) {
         if let Some(item) = self.get_selected_item() {
             if item.node.is_dir {
@@ -167,10 +152,6 @@ impl AppState {
         }
     }
 
-    pub fn clear_marks(&mut self) {
-        self.marked_files.clear();
-    }
-
     pub fn clear_playlist(&mut self) {
         self.playlist.clear();
         self.playlist_index = 0;
@@ -469,7 +450,6 @@ fn flatten_tree(nodes: &[FileTreeNode], depth: usize, expanded_dirs: &HashSet<Pa
         result.push(FlattenedItem {
             node: node.clone(),
             depth,
-            is_expanded,
         });
 
         if node.is_dir && !node.children.is_empty() && is_expanded {