Function ensure_nodegroup 

pub fn ensure_nodegroup(
    all_values_map: &HashMap<String, Option<bool>>,
    all_nodegroups: &mut HashMap<String, bool>,
    nodegroup_id: &str,
    add_if_missing: bool,
    nodegroup_permissions: &HashMap<String, PermissionRule>,
    do_implied_nodegroups: bool,
    model: &dyn ModelAccess,
    tiles_store: &HashMap<String, StaticTile>,
) -> Result<EnsureNodegroupResult, SemanticChildError>

Standalone ensure_nodegroup — processes a single nodegroup and returns structured values.

Extracted from ResourceInstanceWrapperCore::ensure_nodegroup so that WASM (and other bindings) can call this directly with their own tile store.