Function extract_all_target_groups 

pub fn extract_all_target_groups(sat_file: &Value) -> Vec<String>

Read every HSM group name referenced anywhere in a SAT file — across all images[] and session_templates[] entries — deduplicated.

Returns an empty Vec for a SAT file with no groups (or no images / session_templates sections at all).

Used by crate::server::handlers::post_sat_validate to enforce HSM-group access before delegating to the backend.