feat(helixo): wire UI to real engines + 31 tests

v3/plugins/helixo/app/.gitignore

@@ -0,0 +1,4 @@
+node_modules/
+.next/
+dist/
+next-env.d.ts

v3/plugins/helixo/app/next.config.mjs

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+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  transpilePackages: ['@claude-flow/plugin-helixo'],
+};
+export default nextConfig;