manager: add optional agent param to GetLooseEnds

GetLooseEnds now takes agent: Option<String>:
- None   = manager's own loose ends (default; the bug fix)
- Some("*")    = hive-wide view (every approval/question/reminder)
- Some("name") = that agent's loose ends

The get_loose_ends MCP tool exposes this as an optional agent arg, so
the manager can still scan the whole swarm on demand. The web UI and
post-turn counts pass None (manager's own).

hive-ag3nt/src/web_ui.rs

@@ -409,7 +409,9 @@ async fn api_loose_ends(State(state): State<AppState>) -> Response {
         Flavor::Manager => {
             match client::request::<_, hive_sh4re::ManagerResponse>(
                 &state.socket,
-                &hive_sh4re::ManagerRequest::GetLooseEnds,
+                // Manager's own loose ends — the web page is the
+                // manager's page, not a hive-wide console.
+                &hive_sh4re::ManagerRequest::GetLooseEnds { agent: None },
             )
             .await
             {