Fix HAOS light color reverting after timeout

When HA sets a color via turn_on, also update the source's fallback_color
to match. This way when the api_input timeout fires (default 5s), the
stream reverts to the same color instead of black. turn_off resets
fallback to [0,0,0].

Added coordinator.update_source() for PUT /color-strip-sources/{id}.

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

custom_components/wled_screen_controller/light.py

@@ -114,15 +114,22 @@ class ApiInputLight(CoordinatorEntity, LightEntity):
             self._source_id,
             [{"start": 0, "length": 9999, "mode": "solid", "color": scaled}],
         )
+        # Update fallback_color so the color persists beyond the timeout
+        await self.coordinator.update_source(
+            self._source_id, fallback_color=scaled,
+        )
         self._is_on = True
         self.async_write_ha_state()
 
     async def async_turn_off(self, **kwargs: Any) -> None:
-        """Turn off the light by pushing the fallback color."""
-        fallback_color = self._get_fallback_color()
+        """Turn off the light by pushing black and setting fallback to black."""
+        off_color = [0, 0, 0]
         await self.coordinator.push_segments(
             self._source_id,
-            [{"start": 0, "length": 9999, "mode": "solid", "color": fallback_color}],
+            [{"start": 0, "length": 9999, "mode": "solid", "color": off_color}],
+        )
+        await self.coordinator.update_source(
+            self._source_id, fallback_color=off_color,
         )
         self._is_on = False
         self.async_write_ha_state()