fix: change self reference to mutable in save_meta and remove unused imports

Co-authored-by: aider (openai/andrew/openrouter/qwen/qwen3-coder) <aider@aider.chat>

src/meta_plugin/program.rs

@@ -5,7 +5,6 @@ use std::io;
 use std::io::Write;
 use std::process::{Command, Stdio};
 use which::which;
-use rusqlite::Connection;
 
 use crate::meta_plugin::MetaPlugin;