Remove idle color feature, simplify power to turn-off only, fix settings serial port bug

- Remove static/idle color from entire stack (storage, API, processing, UI, CSS, locales)
- Simplify device power button to turn-off only (send black frame, no toggle)
- Send black frame on serial port close (AdalightClient.close)
- Fix settings modal serial port dropdown showing WLED devices due to stale deviceType

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

server/src/wled_controller/static/js/app.js

@@ -30,8 +30,7 @@ import {
 import {
     showSettings, closeDeviceSettingsModal, forceCloseDeviceSettingsModal,
     saveDeviceSettings, updateBrightnessLabel, saveCardBrightness,
-    saveDeviceStaticColor, clearDeviceStaticColor,
-    toggleDevicePower, removeDevice, loadDevices,
+    turnOffDevice, removeDevice, loadDevices,
     updateSettingsBaudFpsHint,
 } from './features/devices.js';
 import {
@@ -149,9 +148,7 @@ Object.assign(window, {
     saveDeviceSettings,
     updateBrightnessLabel,
     saveCardBrightness,
-    saveDeviceStaticColor,
-    clearDeviceStaticColor,
-    toggleDevicePower,
+    turnOffDevice,
     removeDevice,
     loadDevices,
     updateSettingsBaudFpsHint,