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/api/__init__.py

@@ -12,6 +12,7 @@ from .routes.picture_targets import router as picture_targets_router
 from .routes.color_strip_sources import router as color_strip_sources_router
 from .routes.audio import router as audio_router
 from .routes.audio_sources import router as audio_sources_router
+from .routes.value_sources import router as value_sources_router
 from .routes.profiles import router as profiles_router
 
 router = APIRouter()
@@ -24,6 +25,7 @@ router.include_router(picture_sources_router)
 router.include_router(color_strip_sources_router)
 router.include_router(audio_router)
 router.include_router(audio_sources_router)
+router.include_router(value_sources_router)
 router.include_router(picture_targets_router)
 router.include_router(profiles_router)