fix: fix typos and improve error handling in compression engines

Co-authored-by: aider (openai/andrew/openrouter/sonoma-sky-alpha) <aider@aider.chat>

src/modes/diff.rs

@@ -4,8 +4,6 @@
 /// differences using external diff tools.
 use anyhow::{Context, Result};
 use clap::Command;
-use std::io::Read;
-use std::os::fd::FromRawFd;
 use crate::config;
 use crate::services::item_service::ItemService;
 use log::debug;