Fix mobile color picker popup clipping and locale update for tabs/sections

Color picker popover now uses fixed positioning on small screens to
escape the header toolbar overflow container. Section titles, sub-tab
labels, and filter placeholders use data-i18n attributes so they update
automatically on language change. Display picker title switches to
"Select a Device" for engine-owned display lists.

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

server/src/wled_controller/static/locales/ru.json

@@ -38,6 +38,7 @@
   "displays.none": "Нет доступных дисплеев",
   "displays.failed": "Не удалось загрузить дисплеи",
   "displays.picker.title": "Выберите Дисплей",
+  "displays.picker.title.device": "Выберите Устройство",
   "displays.picker.select": "Выберите дисплей...",
   "displays.picker.click_to_select": "Нажмите, чтобы выбрать этот дисплей",
   "displays.picker.adb_connect": "Подключить ADB устройство",