power saving on idle

src/main.cpp

@@ -408,6 +408,13 @@ void loop() {
   if (currentActivity && currentActivity->skipLoopDelay()) {
     yield();  // Give FreeRTOS a chance to run tasks, but return immediately
   } else {
-    delay(10);  // Normal delay when no activity requires fast response
+    static constexpr unsigned long IDLE_POWER_SAVING_MS = 10000;
+    if (millis() - lastActivityTime >= IDLE_POWER_SAVING_MS) {
+      // If we've been inactive for a while, increase the delay to save power
+      delay(50);
+    } else {
+      // Short delay to prevent tight loop while still being responsive
+      delay(10);
+    }
   }
 }