fix: make cmd mutable and remove unused import

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/modes/delete.rs

@@ -4,7 +4,6 @@ use std::path::PathBuf;
 use crate::config;
 use crate::services::error::CoreError;
 use crate::services::item_service::ItemService;
-use clap::error::ErrorKind;
 use clap::Command;
 use log::warn;
 use rusqlite::Connection;