Add static color for simple devices, change auto-shutdown to auto-restore

- Add `static_color` capability to Adalight provider with `set_color()` method
- Add `static_color` field to Device model, DeviceState, and API schemas
- Add GET/PUT `/devices/{id}/color` API endpoints
- Change auto-shutdown behavior: restore device to idle state instead of
  powering off (WLED uses snapshot/restore, Adalight sends static color
  or black frame)
- Rename `_auto_shutdown_device_if_idle` to `_restore_device_idle_state`
- Add inline color picker on device cards for devices with static_color
- Add auto_shutdown toggle to device settings modal
- Update labels from "Auto Shutdown" to "Auto Restore" (en + ru)
- Remove backward-compat KC aliases from ProcessorManager
- Align card action buttons to bottom with flex column layout

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

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

@@ -158,6 +158,9 @@
   "device.health.online": "Online",
   "device.health.offline": "Offline",
   "device.health.checking": "Checking...",
+  "device.static_color": "Idle Color",
+  "device.static_color.hint": "Color shown when device is idle",
+  "device.static_color.clear": "Clear idle color",
   "device.tutorial.start": "Start tutorial",
   "device.tip.metadata": "Device info (LED count, type, color channels) is auto-detected from the device",
   "device.tip.brightness": "Slide to adjust device brightness",
@@ -184,6 +187,8 @@
   "settings.button.cancel": "Cancel",
   "settings.health_interval": "Health Check Interval (s):",
   "settings.health_interval.hint": "How often to check the device status (5-600 seconds)",
+  "settings.auto_shutdown": "Auto Restore:",
+  "settings.auto_shutdown.hint": "Restore device to idle state when targets stop or server shuts down",
   "settings.button.save": "Save Changes",
   "settings.saved": "Settings saved successfully",
   "settings.failed": "Failed to save settings",