Low-level Server support for mcp dev and mcp run command

Currently the mcp dev and mcp run command does not support the low-level Server class. I think it's a better developer experience if we support both classes for these 2 commands, assuming there's no inherent reason for not doing so.

I'm interested in adding support for the low-level Server to both mcp dev and mcp run and I would like seek the maintainer's guidance on this. It looks like the only thing missing is the dependencies field, which is pulled from the Settings class and does not exist in the low-level Server. I'm thinking about adding a similar Settings class to server/lowlevel/server.py and thus introducing the dependencies field. The downside is more complexity in server/lowlevel/server.py which I'm not sure if it's acceptable to the maintainers and falls in line with the long term roadmap for the code base.

Please advise. Thanks.

まず、mcp dev と mcp run コマンドのエントリポイントをたどり、それぞれが高レベルと低レベルの Server クラスをどのように扱っているかを比較します。server/lowlevel/server.py と既存の Settings クラスを読んで、不足している dependencies フィールドを理解します。完了条件は、設計について maintainer の合意が得られ、両方のコマンドで低レベルの Server がサポートされていることを確認できることです。