Remove embedded admin UI and redirect admins to standalone ops app.

Extract admin routes from the main SPA, add plaza-api bootstrap module, and track ops pnpm lockfile.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/routes/RequireAdmin.tsx

@@ -1,23 +0,0 @@
-import { useEffect } from 'react';
-import { useNavigate } from 'react-router-dom';
-import type { PortalUser } from '../types';
-
-export function RequireAdmin({
-  user,
-  children,
-}: {
-  user: PortalUser | null;
-  children: React.ReactNode;
-}) {
-  const navigate = useNavigate();
-  const allowed = user?.role === 'admin';
-
-  useEffect(() => {
-    if (!allowed) {
-      navigate('/', { replace: true });
-    }
-  }, [allowed, navigate]);
-
-  if (!allowed) return null;
-  return children;
-}