恢复 is_default_folder/is_editable 方法及 enter() 方法（重写遗漏的部分）

Author: Navinatte

phira/src/page/favorites.rs

@@ -178,6 +178,19 @@ impl FavoritesPage {
         }
     }
 
+    // 默认收藏夹仅可修改封面 || The default favorites folder can only modify the cover
+    fn is_default_folder(folder_name: &Option<String>) -> bool {
+        matches!(folder_name, Some(name) if name == DEFAULT_FAVORITES_KEY)
+    }
+
+    // 自定义收藏夹可编辑（重命名、删除、修改封面） || Custom favorites folders can be edited (rename, delete, modify cover)
+    fn is_editable(folder_name: &Option<String>) -> bool {
+        match folder_name {
+            None => false,
+            Some(name) => name != DEFAULT_FAVORITES_KEY,
+        }
+    }
+
     fn has_menu(folder_name: &Option<String>) -> bool {
         folder_name.is_some()
     }

phira/src/page/library.rs

@@ -285,6 +285,10 @@ impl Page for LibraryPage {
         tl!("label")
     }
 
+    fn enter(&mut self, _s: &mut SharedState) -> Result<()> {
+        Ok(())
+    }
+
     fn on_result(&mut self, res: Box<dyn Any>, s: &mut SharedState) -> Result<()> {
         let _res = match res.downcast::<bool>() {
             Err(res) => res,