Function execute_config_hook 

pub fn execute_config_hook(
    hook_name: &str,
    template: &str,
    vars: &HookVars,
    project_dir: &Path,
)

Execute a config-based hook command asynchronously.

The command is expanded with template variables, then spawned via sh -c. The subprocess runs in the background — we don’t wait for it. Any errors during spawn are logged to stderr but never propagated.

Arguments

• hook_name - Name for logging (e.g., “on_close”, “on_fail”)
• template - The command template with {var} placeholders
• vars - Template variables to expand
• project_dir - Working directory for the subprocess