[Enhance] [Refactor] Add API about characters

- Add API endpoints about characters
- Some small changes in refactoring

latest version/api/api_code.py

@@ -23,6 +23,8 @@ CODE_MSG = {
     -122: 'Item already exists',
     -123: 'The collection already has this item',
     -124: 'The collection does not have this item',
+    -130: 'No such character',
+    -131: 'Invalid skill ID',
     -200: 'No permission',  # 2xx用户相关错误
     -201: 'Wrong username or password',
     -202: 'User is banned',