Rename picture-targets to output-targets across entire codebase

Rename all Python modules, classes, API endpoints, config keys, frontend
fetch URLs, and Home Assistant integration URLs from picture-targets to
output-targets. Store loads both new and legacy JSON keys for backward
compatibility with existing data files.

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

server/src/wled_controller/core/processing/target_processor.py

@@ -1,7 +1,7 @@
 """Abstract base class for target processors.
 
 A TargetProcessor encapsulates the processing loop and state for a single
-picture target. Concrete subclasses (WledTargetProcessor, KCTargetProcessor)
+output target. Concrete subclasses (WledTargetProcessor, KCTargetProcessor)
 implement the target-specific capture→process→output pipeline.
 
 ProcessorManager creates and owns TargetProcessor instances, delegating

server/src/wled_controller/core/scenes/scene_activator.py

@@ -6,7 +6,7 @@ These functions are used by both the scene-presets API route and the automation
 from typing import List, Optional, Set, Tuple
 
 from wled_controller.core.processing.processor_manager import ProcessorManager
-from wled_controller.storage.picture_target_store import PictureTargetStore
+from wled_controller.storage.output_target_store import OutputTargetStore
 from wled_controller.storage.scene_preset import (
     ScenePreset,
     TargetSnapshot,
@@ -17,7 +17,7 @@ logger = get_logger(__name__)
 
 
 def capture_current_snapshot(
-    target_store: PictureTargetStore,
+    target_store: OutputTargetStore,
     processor_manager: ProcessorManager,
     target_ids: Optional[Set[str]] = None,
 ) -> List[TargetSnapshot]:
@@ -45,7 +45,7 @@ def capture_current_snapshot(
 
 async def apply_scene_state(
     preset: ScenePreset,
-    target_store: PictureTargetStore,
+    target_store: OutputTargetStore,
     processor_manager: ProcessorManager,
 ) -> Tuple[str, List[str]]:
     """Apply a scene preset's state to the system.