Rework API input CSS: segments, remove led_count, HAOS light, test preview

API Input CSS rework:
- Remove led_count field from ApiInputColorStripSource (always auto-sizes)
- Add segment-based payload: solid, per_pixel, gradient modes
- Segments applied in order (last wins on overlap), auto-grow buffer
- Backward compatible: legacy {"colors": [...]} still works
- Pydantic validation: mode-specific field requirements

Test preview:
- Enable test preview button on api_input cards
- Hide LED/FPS controls for api_input (sender controls those)
- Show input source selector for all CSS tests (preselected)
- FPS sparkline chart using shared createFpsSparkline (same as target cards)
- Server only sends frames when push_generation changes (no idle frames)

HAOS integration:
- New light.py: ApiInputLight entity per api_input source (RGB + brightness)
- turn_on pushes solid segment, turn_off pushes fallback color
- Register wled_screen_controller.set_leds service for arbitrary segments
- New services.yaml with field definitions
- Coordinator: push_colors() and push_segments() methods
- Platform.LIGHT added to platforms list

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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

@@ -312,6 +312,10 @@
   "device.tip.webui": "Открыть встроенный веб-интерфейс устройства для расширенной настройки",
   "device.tip.add": "Нажмите, чтобы добавить новое LED устройство",
   "settings.title": "Настройки",
+  "settings.tab.general": "Основные",
+  "settings.tab.backup": "Бэкап",
+  "settings.tab.mqtt": "MQTT",
+  "settings.logs.open_viewer": "Открыть логи",
   "settings.general.title": "Основные Настройки",
   "settings.capture.title": "Настройки Захвата",
   "settings.capture.saved": "Настройки захвата обновлены",
@@ -1076,6 +1080,7 @@
   "color_strip.test.error": "Не удалось подключиться к потоку предпросмотра",
   "color_strip.test.led_count": "Кол-во LED:",
   "color_strip.test.fps": "FPS:",
+  "color_strip.test.receive_fps": "Частота приёма",
   "color_strip.test.apply": "Применить",
   "color_strip.test.composite": "Композит",
   "color_strip.preview.title": "Предпросмотр",