Function clear_stale_pkgbuild_checks_for_selection 

pub fn clear_stale_pkgbuild_checks_for_selection(
    app: &mut AppState,
    selected_package: &str,
)

What: Drop PKGBUILD check results when they belong to a different package than the current selection.

Inputs:

• app: Application state holding check status and findings.
• selected_package: Name of the package now highlighted in the results list.

Output:

• Mutates app to idle check state with empty findings when the last check target does not match.

Details:

• Compares selected_package to AppState::pkgb_check_last_package_name, which is set when a run starts and when results arrive. Keeps results when the user is still on the same package.