fix: remove deprecated default_config_path function

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

src/config.rs

@@ -225,11 +225,6 @@ impl Settings {
         }
     }
 
-    /// Get the default config file path
-    pub fn default_config_path() -> Result<PathBuf> {
-        let xdg_dirs = xdg::BaseDirectories::with_prefix("keep")?;
-        Ok(xdg_dirs.get_config_home().join("config.yml"))
-    }
 
     /// Get server password from password_file or directly from config if configured
     pub fn get_server_password(&self) -> Result<Option<String>> {