Add value sources for dynamic brightness control on LED targets

Introduces a new Value Source entity that produces a scalar float (0.0-1.0)
for dynamic brightness modulation. Three subtypes: Static (constant),
Animated (sine/triangle/square/sawtooth waveform), and Audio-reactive
(RMS/peak/beat from mono audio source). Value sources can be optionally
attached to LED targets to control brightness each frame.

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

server/src/wled_controller/storage/wled_picture_target.py

@@ -15,6 +15,7 @@ class WledPictureTarget(PictureTarget):
 
     device_id: str = ""
     color_strip_source_id: str = ""
+    brightness_value_source_id: str = ""
     fps: int = 30                   # target send FPS (1-90)
     keepalive_interval: float = 1.0 # seconds between keepalive sends when screen is static
     state_check_interval: int = DEFAULT_STATE_CHECK_INTERVAL
@@ -29,11 +30,13 @@ class WledPictureTarget(PictureTarget):
                 fps=self.fps,
                 keepalive_interval=self.keepalive_interval,
                 state_check_interval=self.state_check_interval,
+                brightness_value_source_id=self.brightness_value_source_id,
             )
 
     def sync_with_manager(self, manager, *, settings_changed: bool,
                           css_changed: bool = False,
-                          device_changed: bool = False) -> None:
+                          device_changed: bool = False,
+                          brightness_vs_changed: bool = False) -> None:
         """Push changed fields to the processor manager."""
         if settings_changed:
             manager.update_target_settings(self.id, {
@@ -45,8 +48,11 @@ class WledPictureTarget(PictureTarget):
             manager.update_target_css(self.id, self.color_strip_source_id)
         if device_changed:
             manager.update_target_device(self.id, self.device_id)
+        if brightness_vs_changed:
+            manager.update_target_brightness_vs(self.id, self.brightness_value_source_id)
 
     def update_fields(self, *, name=None, device_id=None, color_strip_source_id=None,
+                      brightness_value_source_id=None,
                       fps=None, keepalive_interval=None, state_check_interval=None,
                       description=None, **_kwargs) -> None:
         """Apply mutable field updates for WLED targets."""
@@ -55,6 +61,8 @@ class WledPictureTarget(PictureTarget):
             self.device_id = device_id
         if color_strip_source_id is not None:
             self.color_strip_source_id = color_strip_source_id
+        if brightness_value_source_id is not None:
+            self.brightness_value_source_id = brightness_value_source_id
         if fps is not None:
             self.fps = fps
         if keepalive_interval is not None:
@@ -71,6 +79,7 @@ class WledPictureTarget(PictureTarget):
         d = super().to_dict()
         d["device_id"] = self.device_id
         d["color_strip_source_id"] = self.color_strip_source_id
+        d["brightness_value_source_id"] = self.brightness_value_source_id
         d["fps"] = self.fps
         d["keepalive_interval"] = self.keepalive_interval
         d["state_check_interval"] = self.state_check_interval
@@ -95,6 +104,7 @@ class WledPictureTarget(PictureTarget):
             target_type="led",
             device_id=data.get("device_id", ""),
             color_strip_source_id=css_id,
+            brightness_value_source_id=data.get("brightness_value_source_id", ""),
             fps=data.get("fps", 30),
             keepalive_interval=data.get("keepalive_interval", data.get("standby_interval", 1.0)),
             state_check_interval=data.get("state_check_interval", DEFAULT_STATE_CHECK_INTERVAL),