HA integration: fix reload loop, parallel device fetch, WS guards, translations

- Fix indentation bug causing scenes device to not register
- Use nonlocal tracking to prevent infinite reload loops on target/scene changes
- Guard WS start/stop to avoid redundant connections
- Parallel device brightness fetching via asyncio.gather
- Route set_leds service to correct coordinator by source ID
- Remove stale pattern cache, reuse single timeout object
- Fix translations structure for light/select entities
- Unregister service when last config entry unloaded

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

custom_components/wled_screen_controller/button.py

@@ -65,10 +65,9 @@ class SceneActivateButton(CoordinatorEntity, ButtonEntity):
         """Return if entity is available."""
         if not self.coordinator.data:
             return False
-        return any(
-            p["id"] == self._preset_id
-            for p in self.coordinator.data.get("scene_presets", [])
-        )
+        return self._preset_id in {
+            p["id"] for p in self.coordinator.data.get("scene_presets", [])
+        }
 
     async def async_press(self) -> None:
         """Activate the scene preset."""