NEKOとDOGの処理について

せっかくファイル分けしているのでそこに処理を投げませんかというお気持ちです、

NEKOの例でいうと、
```python
#Message.py
if message_main in src.command.message_list_NEKO:
await src.NEKO.send_neko(message)
```
これは
```python
content = message.content

if src.NEKO.content_is_command(content):
await src.NEKO.send_neko(message)
```
※関数名は適当
こういう形でもいいし、条件判断も関数内に入れて1文で終わらす形でもいいかな

Start by reading Message.py and the existing src.command.message_list_NEKO and src.NEKO.send_neko paths. Trace how NEKO and DOG commands are currently selected, then decide how the command check should be delegated to the corresponding module; done means the routing remains correct while the processing logic is moved out of Message.py.

Written by the indexing model from the issue text.