fix: Add HashMap import to config module

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

src/config.rs

@@ -1,5 +1,6 @@
 use std::path::PathBuf;
 use std::fs;
+use std::collections::HashMap;
 use anyhow::{Result, Context};
 use serde::{Deserialize, Serialize};
 use log::{debug, error};