Jar依存に置き換える

別bot(Prefix manager)で、このbotの`lib/`以下をJarにしたものを使用しているので、どうせならこっちもJarにして`lib/`以下を別のリポで管理したい

Start by reviewing the lib/ directory and how this bot currently uses it, then compare that arrangement with the Jar used by the separate Prefix manager bot. Clarify the intended separate repository, Jar packaging, dependency location, and ownership before changing anything; done means this bot consumes the external Jar instead of managing lib/ directly.

Written by the indexing model from the issue text.