Function refresh_installed_cache 

pub async fn refresh_installed_cache()

What: Refresh the process-wide cache of installed package names using pacman -Qq.

Inputs:

• None (spawns a blocking task to run pacman)

Output:

• Updates the global installed-name set; ignores errors.

Details:

• Parses command stdout into a HashSet and swaps it into the shared cache under a write lock.