fix(#1013): make validate_groups private (only called by set_groups)

hive-c0re/src/tool_groups.rs

@@ -72,7 +72,7 @@ pub fn write(map: &BTreeMap<String, Vec<String>>) -> std::io::Result<()> {
 /// Validate a slice of group name strings against `ToolGroup::ALL`.
 /// Returns `Ok(())` when all names are known, or `Err` listing the
 /// unrecognised names so callers can surface a useful error message.
-pub fn validate_groups(groups: &[String]) -> anyhow::Result<()> {
+fn validate_groups(groups: &[String]) -> anyhow::Result<()> {
     let valid: std::collections::BTreeSet<&str> =
         hive_sh4re::ToolGroup::ALL.iter().map(|g| g.as_str()).collect();
     let unknown: Vec<&str> = groups