hive-c0re: scrub manager-surface cookies + SetParent doc fix (#715 batch 7)

hive-c0re/src/main.rs

@@ -84,8 +84,9 @@ enum Cmd {
     Deny { id: i64 },
     /// Move an agent in the topology tree. Set `--parent` to a new
     /// parent agent name; pass `--root` to promote the agent to root
-    /// (no parent). Refuses cycles, unknown agents, and any attempt
-    /// to reparent the manager.
+    /// (no parent). Refuses cycles and unknown agents. The manager
+    /// is reparentable like any other agent — its privileges come
+    /// from the privileged MCP socket, not its tree position.
     SetParent {
         child: String,
         /// New parent agent name. Mutually exclusive with `--root`.