Cancel in-flight diagnostic poll when user selects a new port

Previously switching ports while a diagnostic was running left the
setInterval timer active, causing the result to be written into the
old (now detached) DOM elements and never shown to the user.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/inspector.html

@@ -218,6 +218,7 @@ let _apiData        = null;
 function selectPort(el) {
   const swName = el.dataset.switch;
   const idx    = parseInt(el.dataset.portIdx, 10);
+  if (_diagPollTimer) { clearInterval(_diagPollTimer); _diagPollTimer = null; }
   document.querySelectorAll('.switch-port-block.selected')
     .forEach(e => e.classList.remove('selected'));
   el.classList.add('selected');

templates/links.html

@@ -548,7 +548,7 @@ function checkLinksStale(updatedStr) {
 async function loadLinks() {
   try {
     const data = await lt.api.get('/api/links');
-    if (!data.hosts && !data.unifi_switches) {
+    if ((!data.hosts || !Object.keys(data.hosts).length) && (!data.unifi_switches || !Object.keys(data.unifi_switches).length)) {
       document.getElementById('links-container').innerHTML =
         '<div class="link-no-data">No link data yet — monitor has not completed a full cycle.</div>';
       return;