perf(es3c28p): LVGL 512KB PSRAM cache + display charging toggle

- LVGL image cache 512KB + header cache 16 on PSRAM (was PNG bottleneck, c4ec7ead)
- DisplaySettings.disableScreensaverWhenCharging persisted, checked via PowerDevice::IsCharging
- Display app: 'Disable on charging' toggle under Display settings, auto-disabled when timeout off
- DisplayIdle: skip screensaver while charging, auto-stop if plugging in while dimmed
- Keeps upstream full-DTS board clean, no JPEG decoder, no BT HID combo per user

Tactility/Source/service/displayidle/DisplayIdle.cpp

@@ -11,6 +11,7 @@
 #include <tactility/log.h>
 #include <Tactility/CoreDefines.h>
 #include <Tactility/hal/display/DisplayDevice.h>
+#include <Tactility/hal/power/PowerDevice.h>
 #include <Tactility/lvgl/LvglSync.h>
 #include <Tactility/service/ServiceContext.h>
 #include <Tactility/service/ServiceManifest.h>
@@ -28,6 +29,23 @@ static std::shared_ptr<hal::display::DisplayDevice> getDisplay() {
     return hal::findFirstDevice<hal::display::DisplayDevice>(hal::Device::Type::Display);
 }
 
+static bool isDeviceCharging() {
+    bool charging = false;
+    hal::findDevices<hal::power::PowerDevice>(hal::Device::Type::Power, [&charging](const auto& power) {
+        if (!power->supportsMetric(hal::power::PowerDevice::MetricType::IsCharging)) {
+            return true;
+        }
+        hal::power::PowerDevice::MetricData data;
+        if (power->getMetric(hal::power::PowerDevice::MetricType::IsCharging, data) && data.valueAsBool) {
+            charging = true;
+            return false;
+        }
+        return true;
+    });
+    return charging;
+}
+
+
 void DisplayIdleService::stopScreensaverCb(lv_event_t* e) {
     auto* self = static_cast<DisplayIdleService*>(lv_event_get_user_data(e));
     lv_event_stop_bubbling(e);
@@ -123,6 +141,7 @@ void DisplayIdleService::updateScreensaver() {
     }
 }
 
+
 void DisplayIdleService::tick() {
     if (!lvgl::lock(100)) {
         return;
@@ -138,16 +157,13 @@ void DisplayIdleService::tick() {
     }
 
     uint32_t inactive_ms = 0;
-
     inactive_ms = lv_display_get_inactive_time(nullptr);
 
     // Only update if not stopping (prevents lag on touch)
     if (displayDimmed && screensaverOverlay && !stopScreensaverRequested.load(std::memory_order_acquire)) {
-        // Check if screensaver should auto-off after 5 minutes
         if (!backlightOff) {
             screensaverActiveCounter++;
             if (screensaverActiveCounter >= SCREENSAVER_AUTO_OFF_TICKS) {
-                // Stop screensaver animation and turn off backlight
                 if (screensaver) {
                     screensaver->stop();
                     screensaver.reset();
@@ -165,38 +181,51 @@ void DisplayIdleService::tick() {
 
     lvgl::unlock();
 
-    // Check stop request early for faster response
     if (stopScreensaverRequested.load(std::memory_order_acquire)) {
         stopScreensaver();
         return;
     }
 
     auto display = getDisplay();
-    if (display != nullptr && display->supportsBacklightDuty()) {
-        if (!cachedDisplaySettings.backlightTimeoutEnabled || cachedDisplaySettings.backlightTimeoutMs == 0) {
-            if (displayDimmed) {
+    bool supportsBacklight = display != nullptr && display->supportsBacklightDuty();
+
+    if (!cachedDisplaySettings.backlightTimeoutEnabled || cachedDisplaySettings.backlightTimeoutMs == 0) {
+        if (displayDimmed) {
+            if (supportsBacklight && display != nullptr) {
                 display->setBacklightDuty(cachedDisplaySettings.backlightDuty);
-                displayDimmed = false;
             }
-        } else {
-            if (!displayDimmed && inactive_ms >= cachedDisplaySettings.backlightTimeoutMs) {
+            displayDimmed = false;
+        }
+    } else if (supportsBacklight) {
+        bool charging_blocks = cachedDisplaySettings.disableScreensaverWhenCharging && isDeviceCharging();
+
+        if (!displayDimmed && inactive_ms >= cachedDisplaySettings.backlightTimeoutMs) {
+            if (charging_blocks) {
+                // Skip screensaver while charging
+            } else {
                 if (!lvgl::lock(100)) {
-                    return; // Retry on next tick
+                    return;
                 }
                 activateScreensaver();
                 lvgl::unlock();
-                // Turn off backlight for "None" screensaver (just black screen)
                 if (cachedDisplaySettings.screensaverType == settings::display::ScreensaverType::None) {
-                    display->setBacklightDuty(0);
+                    if (display != nullptr) {
+                        display->setBacklightDuty(0);
+                    }
                 }
                 displayDimmed = true;
-            } else if (displayDimmed && (inactive_ms < kWakeActivityThresholdMs)) {
+            }
+        } else if (displayDimmed) {
+            if (inactive_ms < kWakeActivityThresholdMs) {
+                stopScreensaver();
+            } else if (charging_blocks) {
                 stopScreensaver();
             }
         }
     }
 }
 
+
 bool DisplayIdleService::onStart(ServiceContext& service) {
     // Seed random number generator for varied screensaver patterns
     srand(static_cast<unsigned int>(time(nullptr)));