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/Include/Tactility/settings/DisplaySettings.h

@@ -1,44 +1,32 @@
 #pragma once
-
 #include <src/display/lv_display.h>
-
 namespace tt::settings::display {
-
 enum class Orientation {
-    // In order of rotation (to make it easier to convert to LVGL rotation)
     Landscape,
     Portrait,
     LandscapeFlipped,
     PortraitFlipped,
 };
-
 enum class ScreensaverType {
-    None,           // Just black screen
+    None,
     BouncingBalls,
     Mystify,
     MatrixRain,
     StackChan,
-    Count           // Sentinel for bounds checking - must be last
+    Count
 };
-
 struct DisplaySettings {
     Orientation orientation;
     uint8_t gammaCurve;
     uint8_t backlightDuty;
     bool backlightTimeoutEnabled;
-    uint32_t backlightTimeoutMs; // 0 = Never
+    uint32_t backlightTimeoutMs;
     ScreensaverType screensaverType = ScreensaverType::BouncingBalls;
+    bool disableScreensaverWhenCharging = false;
 };
-
-/** Compares default settings with the function parameter to return the difference */
 lv_display_rotation_t toLvglDisplayRotation(Orientation orientation);
-
 bool load(DisplaySettings& settings);
-
 DisplaySettings loadOrGetDefault();
-
 DisplaySettings getDefault();
-
 bool save(const DisplaySettings& settings);
-
-} // namespace
+}