增加项目类型习题+fix buig

src/skill_tree/tree.py

@@ -437,7 +437,7 @@ class TreeWalker:
             mfile = base + ".json"
             meta_path = os.path.join(section_path, mfile)
             md_file = os.path.join(section_path, e)
-            self.ensure_exercises_meta(meta_path, source, md_file)
+            meta = self.ensure_exercises_meta(meta_path, source, md_file)
             export = config.get("export", [])
             if mfile not in export and self.name != "algorithm":
                 export.append(mfile)
@@ -523,6 +523,7 @@ class TreeWalker:
                 "exercise_id": uuid.uuid4().hex,
             }
         dump_json(meta_path, meta, True, True)
+        return meta
 
     def default_notebook(self):
         if self.enable_notebook is not None: