UN-3234 [FIX] Add beta tag to agentic prompt studio navigation item (#1817)

Tag was removed in PR #1768 (sidebar UX refactor). Re-adds it using
the existing el.tag pattern already present in the sidebar renderer.

Author: Deepak-Kesavan

frontend/src/components/navigations/side-nav-bar/SideNavBar.jsx

@@ -494,6 +494,7 @@ const SideNavBar = ({ collapsed, setCollapsed }) => {
       active: globalThis.location.pathname.startsWith(
         `/${orgName}/agentic-prompt-studio`,
       ),
+      tag: "BETA",
     });
   }