Function get_installed_version 

pub fn get_installed_version(name: &str) -> Result<String, String>

What: Retrieve the locally installed version of a package.

Inputs:

• name: Package to query via pacman -Q.

Output:

• Returns the installed version string on success; otherwise an error message.

Errors

• Returns Err when pacman -Q command execution fails (I/O error)
• Returns Err when the package is not found or not installed
• Returns Err when the version string cannot be parsed from command output

Details:

• Normalizes versions by removing revision suffixes to facilitate requirement comparisons.