Drop the duplicate openvibe.network preconnect (#279)

ddiff --git a/apps/gateway/server/pages/site.js b/apps/gateway/server/pages/site.js
iindex 4097b83..5c06b87 100644
---- a/apps/gateway/server/pages/site.js
++++ b/apps/gateway/server/pages/site.js
@@@ -262,7 +262,6 @@ function shell({ head, body, families, agent = false }) {
  ${head}
  ${appIcon.headTags({ site: 'tools', iconBase: '/assets' })}
  <link rel="alternate" type="application/json" href="${SITE}/api/catalog.json" title="Tool catalog">
--<link rel="preconnect" href="https://openvibe.network">
  <script src="${ovServe.url('theme-loader.js')}" defer></script>
  <link rel="stylesheet" href="${ovServe.url('kit.css')}">
  <style>${CSS}</style></head><body>${spriteSvg}
ddiff --git a/apps/gateway/test/preconnect.test.js b/apps/gateway/test/preconnect.test.js
nnew file mode 100644
iindex 0000000..13f32e2
---- /dev/null
++++ b/apps/gateway/test/preconnect.test.js
@@@ -0,0 +1,21 @@
++'use strict';
++// Exactly one preconnect to openvibe.network, with crossorigin: the Shared SEO head already adds
++// one; a second one (without crossorigin) opens a wasted connection.
++const assert = require('assert');
++const http = require('http');
++const express = require('express');
++const site = require('../server/pages/site');
++
++(async () => {
++    const app = express();
++    app.use(site.createSiteRouter());
++    const srv = http.createServer(app);
++    await new Promise((r) => srv.listen(0, '127.0.0.1', r));
++    try {
++        const home = await (await fetch(`http://127.0.0.1:${srv.address().port}/`)).text();
++        const pcs = [...home.matchAll(/<link rel="preconnect" href="https:\/\/openvibe\.network"[^>]*>/g)].map((m) => m[0]);
++        assert.strictEqual(pcs.length, 1, `exactly one openvibe.network preconnect, saw ${pcs.length}: ${pcs.join(' | ')}`);
++        assert.ok(pcs[0].includes('crossorigin'), 'the preconnect carries crossorigin (CORS fetches)');
++    } finally { srv.close(); }
++    console.log('preconnect: one crossorigin hint to openvibe.network');
++})().catch((e) => { console.error(e); process.exit(1); });