fix: address argus+mara review on #1243 — stale docs, MANAGER_DEFAULT refs, ruth migration

hive-c0re/src/meta.rs

@@ -755,7 +755,7 @@ where
             .map_or_else(|| "null".to_owned(), |p| format!("\"{p}\""));
         // Emit `toolGroups = "group1,group2"` when the operator has
         // explicitly configured groups for this agent. Absent entry = null
-        // = harness falls back to its role default (no env var emitted,
+        // = harness falls back to AGENT_DEFAULT (no env var emitted,
         // no rebuild cascade for agents whose groups haven't changed).
         let groups = tool_groups_map.get(&spec.name).cloned().unwrap_or_default();
         let tool_groups_attr = if groups.is_empty() {