Add display brightness and power control

- New display service with DDC/CI brightness and power control via screen_brightness_control and monitorcontrol
- New /api/display/* endpoints (monitors, brightness, power)
- Display tab in WebUI with per-monitor brightness sliders and power toggle
- EDID resolution parsing to distinguish same-name monitors
- Throttled brightness slider (50ms) matching volume control pattern

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

media_server/static/locales/ru.json

@@ -119,6 +119,12 @@
   "tab.quick_actions": "Действия",
   "tab.scripts": "Скрипты",
   "tab.callbacks": "Колбэки",
+  "tab.display": "Дисплей",
+  "display.loading": "Загрузка мониторов...",
+  "display.error": "Не удалось загрузить мониторы",
+  "display.no_monitors": "Мониторы не обнаружены",
+  "display.power_on": "Включить",
+  "display.power_off": "Выключить",
   "browser.title": "Медиа Браузер",
   "browser.home": "Главная",
   "browser.manage_folders": "Управление папками",