fix(#2190): replace MANAGER_AGENT fallbacks with "operator" for attribution

- loose_ends.rs: NULL submitter on legacy approval rows → "operator"
- questions.rs: NULL submitter on cancel_loose_end → "operator"
- server.rs: HostRequest::RequestSpawn submitter → "operator"
- dashboard.rs: web-UI spawn submitter → "operator"
- socket_server.rs: submit_init_config with no declared parent → "operator"
- mcp.rs: drop MANAGER_AGENT exception from check_send_allowed; keep <parent> only

hive-c0re/src/server.rs

@@ -85,7 +85,7 @@ async fn dispatch(req: &HostRequest, coord: Arc<Coordinator>) -> HostResponse {
                     hive_sh4re::ApprovalKind::Spawn,
                     "",
                     None,
-                    hive_sh4re::MANAGER_AGENT,
+                    "operator",
                 )?;
                 tracing::info!(%id, %name, "spawn approval queued");
                 HostResponse::success()