perf: pause polling intervals when browser tab is hidden

- Replace raw setInterval with startPolling/stopPolling functions
- Add visibilitychange listener to pause when tab is hidden
- Immediately refresh data when tab becomes visible again
- Saves bandwidth and CPU when the dashboard is in background

bot/static/index.html

@@ -1908,10 +1908,33 @@ document.addEventListener('DOMContentLoaded', function() {
     }, { passive: false });
   }
   
-  // Set up periodic updates
-  setInterval(loadStatus, 10000);
-  setInterval(loadLogs, 5000);
-  setInterval(loadActiveArguments, 5000);  // Refresh active arguments
+  // Set up periodic updates with visibility-aware polling
+  let statusInterval, logsInterval, argsInterval;
+  
+  function startPolling() {
+    if (!statusInterval) statusInterval = setInterval(loadStatus, 10000);
+    if (!logsInterval) logsInterval = setInterval(loadLogs, 5000);
+    if (!argsInterval) argsInterval = setInterval(loadActiveArguments, 5000);
+  }
+  
+  function stopPolling() {
+    clearInterval(statusInterval); statusInterval = null;
+    clearInterval(logsInterval); logsInterval = null;
+    clearInterval(argsInterval); argsInterval = null;
+  }
+  
+  document.addEventListener('visibilitychange', () => {
+    if (document.hidden) {
+      stopPolling();
+      console.log('⏸ Tab hidden — polling paused');
+    } else {
+      loadStatus(); loadLogs(); loadActiveArguments();
+      startPolling();
+      console.log('▶️ Tab visible — polling resumed');
+    }
+  });
+  
+  startPolling();
 });
 
 // Utility functions