feat: color value source test visualization

WS now sends color RGB data for color-type streams. Test modal renders
a color history swatch strip below the chart, colors the chart line and
fill area with the current output color, and shows rgb() in the stats.
Works for static_color, animated_color, and adaptive_time_color sources.

server/src/wled_controller/api/routes/value_sources.py

@@ -47,6 +47,7 @@ from wled_controller.storage.value_source import (
 from wled_controller.storage.value_source_store import ValueSourceStore
 from wled_controller.storage.output_target_store import OutputTargetStore
 from wled_controller.core.processing.processor_manager import ProcessorManager
+from wled_controller.core.processing.value_stream import ValueStream
 from wled_controller.utils import get_logger
 from wled_controller.storage.base_store import EntityNotFoundError
 
@@ -381,10 +382,21 @@ async def test_value_source_ws(
     await websocket.accept()
     logger.info(f"Value source test WebSocket connected for {source_id}")
 
+    # Detect if this stream produces colors
+    _is_color_stream = (
+        hasattr(stream, "get_color") and type(stream).get_color is not ValueStream.get_color
+    )
+
     try:
         while True:
             value = stream.get_value()
             msg: dict = {"value": round(value, 4)}
+            if _is_color_stream:
+                try:
+                    r, g, b = stream.get_color()
+                    msg["color"] = [int(r), int(g), int(b)]
+                except NotImplementedError:
+                    pass
             if hasattr(stream, "get_raw_value"):
                 raw = stream.get_raw_value()
                 if raw is not None: