Refactor capture engine architecture, rename PictureStream to PictureSource, and split API modules

- Separate CaptureEngine into stateless factory + stateful CaptureStream session
- Add LiveStream/LiveStreamManager for shared capture with reference counting
- Rename PictureStream to PictureSource across storage, API, and UI
- Remove legacy migration logic and unused compatibility code
- Split monolithic routes.py (1935 lines) into 5 focused route modules
- Split schemas.py (480 lines) into 7 schema modules with re-exports
- Extract dependency injection into dedicated dependencies.py

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

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

@@ -0,0 +1,107 @@
+"""Pydantic schemas for API request and response models."""
+
+from .common import (
+    CaptureImage,
+    BorderExtraction,
+    ErrorResponse,
+    PerformanceMetrics,
+    TemplateTestResponse,
+)
+from .system import (
+    DisplayInfo,
+    DisplayListResponse,
+    HealthResponse,
+    VersionResponse,
+)
+from .devices import (
+    Calibration,
+    CalibrationTestModeRequest,
+    CalibrationTestModeResponse,
+    ColorCorrection,
+    DeviceCreate,
+    DeviceListResponse,
+    DeviceResponse,
+    DeviceUpdate,
+    MetricsResponse,
+    ProcessingSettings,
+    ProcessingState,
+)
+from .templates import (
+    EngineInfo,
+    EngineListResponse,
+    TemplateAssignment,
+    TemplateCreate,
+    TemplateListResponse,
+    TemplateResponse,
+    TemplateTestRequest,
+    TemplateUpdate,
+)
+from .filters import (
+    FilterInstanceSchema,
+    FilterOptionDefSchema,
+    FilterTypeListResponse,
+    FilterTypeResponse,
+)
+from .postprocessing import (
+    PostprocessingTemplateCreate,
+    PostprocessingTemplateListResponse,
+    PostprocessingTemplateResponse,
+    PostprocessingTemplateUpdate,
+    PPTemplateTestRequest,
+)
+from .picture_sources import (
+    ImageValidateRequest,
+    ImageValidateResponse,
+    PictureSourceCreate,
+    PictureSourceListResponse,
+    PictureSourceResponse,
+    PictureSourceTestRequest,
+    PictureSourceUpdate,
+)
+
+__all__ = [
+    "CaptureImage",
+    "BorderExtraction",
+    "ErrorResponse",
+    "PerformanceMetrics",
+    "TemplateTestResponse",
+    "DisplayInfo",
+    "DisplayListResponse",
+    "HealthResponse",
+    "VersionResponse",
+    "Calibration",
+    "CalibrationTestModeRequest",
+    "CalibrationTestModeResponse",
+    "ColorCorrection",
+    "DeviceCreate",
+    "DeviceListResponse",
+    "DeviceResponse",
+    "DeviceUpdate",
+    "MetricsResponse",
+    "ProcessingSettings",
+    "ProcessingState",
+    "EngineInfo",
+    "EngineListResponse",
+    "TemplateAssignment",
+    "TemplateCreate",
+    "TemplateListResponse",
+    "TemplateResponse",
+    "TemplateTestRequest",
+    "TemplateUpdate",
+    "FilterInstanceSchema",
+    "FilterOptionDefSchema",
+    "FilterTypeListResponse",
+    "FilterTypeResponse",
+    "PostprocessingTemplateCreate",
+    "PostprocessingTemplateListResponse",
+    "PostprocessingTemplateResponse",
+    "PostprocessingTemplateUpdate",
+    "PPTemplateTestRequest",
+    "ImageValidateRequest",
+    "ImageValidateResponse",
+    "PictureSourceCreate",
+    "PictureSourceListResponse",
+    "PictureSourceResponse",
+    "PictureSourceTestRequest",
+    "PictureSourceUpdate",
+]