Introduce Picture Targets to separate processing from devices

Add PictureTarget entity that bridges PictureSource to output device,
separating processing settings from device connection/calibration state.
This enables future target types (Art-Net, E1.31) and cleanly decouples
"what to stream" from "where to stream."

- Add PictureTarget/WledPictureTarget dataclasses and storage
- Split ProcessorManager into DeviceState (health) + TargetState (processing)
- Add /api/v1/picture-targets endpoints (CRUD, start/stop, settings, metrics)
- Simplify device API (remove processing/settings/metrics endpoints)
- Auto-migrate existing device settings to picture targets on first startup
- Add Targets tab to WebUI with target cards and editor modal
- Add en/ru locale keys for targets UI

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

server/src/wled_controller/api/schemas/__init__.py

@@ -17,14 +17,21 @@ from .devices import (
     Calibration,
     CalibrationTestModeRequest,
     CalibrationTestModeResponse,
-    ColorCorrection,
     DeviceCreate,
     DeviceListResponse,
     DeviceResponse,
+    DeviceStateResponse,
     DeviceUpdate,
-    MetricsResponse,
+)
+from .picture_targets import (
+    ColorCorrection,
+    PictureTargetCreate,
+    PictureTargetListResponse,
+    PictureTargetResponse,
+    PictureTargetUpdate,
     ProcessingSettings,
-    ProcessingState,
+    TargetMetricsResponse,
+    TargetProcessingState,
 )
 from .templates import (
     EngineInfo,
@@ -72,14 +79,19 @@ __all__ = [
     "Calibration",
     "CalibrationTestModeRequest",
     "CalibrationTestModeResponse",
-    "ColorCorrection",
     "DeviceCreate",
     "DeviceListResponse",
     "DeviceResponse",
+    "DeviceStateResponse",
     "DeviceUpdate",
-    "MetricsResponse",
+    "ColorCorrection",
+    "PictureTargetCreate",
+    "PictureTargetListResponse",
+    "PictureTargetResponse",
+    "PictureTargetUpdate",
     "ProcessingSettings",
-    "ProcessingState",
+    "TargetMetricsResponse",
+    "TargetProcessingState",
     "EngineInfo",
     "EngineListResponse",
     "TemplateAssignment",