Introduce ColorStripSource as first-class entity

Extracts color processing and calibration out of WledPictureTarget into a
new PictureColorStripSource entity, enabling multiple LED targets to share
one capture/processing pipeline.

New entities & processing:
- storage/color_strip_source.py: ColorStripSource + PictureColorStripSource models
- storage/color_strip_store.py: JSON-backed CRUD store (prefix css_)
- core/processing/color_strip_stream.py: ColorStripStream ABC + PictureColorStripStream (runs border-extract → map → smooth → brightness/sat/gamma in background thread)
- core/processing/color_strip_stream_manager.py: ref-counted shared stream manager

Modified storage/processing:
- WledPictureTarget simplified to device_id + color_strip_source_id + standby_interval + state_check_interval
- Device model: calibration field removed
- WledTargetProcessor: acquires ColorStripStream from manager instead of running its own pipeline
- ProcessorManager: wires ColorStripStreamManager into TargetContext

API layer:
- New routes: GET/POST/PUT/DELETE /api/v1/color-strip-sources, PUT calibration/test
- Removed calibration endpoints from /devices
- Updated /picture-targets CRUD for new target structure

Frontend:
- New color-strips.js module with CSS editor modal and card rendering
- Calibration modal extended with CSS mode (css-id hidden field + device picker)
- targets.js: Color Strip Sources section added to LED tab; target editor/card updated
- app.js: imports and window globals for CSS + showCSSCalibration
- en.json / ru.json: color_strip.* and targets.section.color_strips keys added

Data migration runs at startup: existing WledPictureTargets are converted to
reference a new PictureColorStripSource created from their old settings.

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

server/src/wled_controller/api/routes/devices.py

@@ -15,9 +15,6 @@ from wled_controller.api.dependencies import (
     get_processor_manager,
 )
 from wled_controller.api.schemas.devices import (
-    Calibration as CalibrationSchema,
-    CalibrationTestModeRequest,
-    CalibrationTestModeResponse,
     DeviceCreate,
     DeviceListResponse,
     DeviceResponse,
@@ -27,10 +24,6 @@ from wled_controller.api.schemas.devices import (
     DiscoverDevicesResponse,
     StaticColorUpdate,
 )
-from wled_controller.core.capture.calibration import (
-    calibration_from_dict,
-    calibration_to_dict,
-)
 from wled_controller.core.processing.processor_manager import ProcessorManager
 from wled_controller.storage import DeviceStore
 from wled_controller.storage.picture_target_store import PictureTargetStore
@@ -54,7 +47,6 @@ def _device_to_response(device) -> DeviceResponse:
         auto_shutdown=device.auto_shutdown,
         static_color=list(device.static_color) if device.static_color else None,
         capabilities=sorted(get_device_capabilities(device.device_type)),
-        calibration=CalibrationSchema(**calibration_to_dict(device.calibration)),
         created_at=device.created_at,
         updated_at=device.updated_at,
     )
@@ -133,7 +125,6 @@ async def create_device(
             device_id=device.id,
             device_url=device.url,
             led_count=device.led_count,
-            calibration=device.calibration,
             device_type=device.device_type,
             baud_rate=device.baud_rate,
             auto_shutdown=device.auto_shutdown,
@@ -534,105 +525,3 @@ async def set_device_color(
 
     return {"color": list(color) if color else None}
 
-
-# ===== CALIBRATION ENDPOINTS =====
-
-@router.get("/api/v1/devices/{device_id}/calibration", response_model=CalibrationSchema, tags=["Calibration"])
-async def get_calibration(
-    device_id: str,
-    _auth: AuthRequired,
-    store: DeviceStore = Depends(get_device_store),
-):
-    """Get calibration configuration for a device."""
-    device = store.get_device(device_id)
-    if not device:
-        raise HTTPException(status_code=404, detail=f"Device {device_id} not found")
-
-    return CalibrationSchema(**calibration_to_dict(device.calibration))
-
-
-@router.put("/api/v1/devices/{device_id}/calibration", response_model=CalibrationSchema, tags=["Calibration"])
-async def update_calibration(
-    device_id: str,
-    calibration_data: CalibrationSchema,
-    _auth: AuthRequired,
-    store: DeviceStore = Depends(get_device_store),
-    manager: ProcessorManager = Depends(get_processor_manager),
-):
-    """Update calibration configuration for a device."""
-    try:
-        # Convert schema to CalibrationConfig
-        calibration_dict = calibration_data.model_dump()
-        calibration = calibration_from_dict(calibration_dict)
-
-        # Update in storage
-        device = store.update_device(device_id, calibration=calibration)
-
-        # Update in manager (also updates active target's cached calibration)
-        try:
-            manager.update_calibration(device_id, calibration)
-        except ValueError:
-            pass
-
-        return CalibrationSchema(**calibration_to_dict(device.calibration))
-
-    except ValueError as e:
-        raise HTTPException(status_code=400, detail=str(e))
-    except Exception as e:
-        logger.error(f"Failed to update calibration: {e}")
-        raise HTTPException(status_code=500, detail=str(e))
-
-
-@router.put(
-    "/api/v1/devices/{device_id}/calibration/test",
-    response_model=CalibrationTestModeResponse,
-    tags=["Calibration"],
-)
-async def set_calibration_test_mode(
-    device_id: str,
-    body: CalibrationTestModeRequest,
-    _auth: AuthRequired,
-    store: DeviceStore = Depends(get_device_store),
-    manager: ProcessorManager = Depends(get_processor_manager),
-):
-    """Toggle calibration test mode for specific edges."""
-    try:
-        device = store.get_device(device_id)
-        if not device:
-            raise HTTPException(status_code=404, detail=f"Device {device_id} not found")
-
-        # Validate edge names and colors
-        valid_edges = {"top", "right", "bottom", "left"}
-        for edge_name, color in body.edges.items():
-            if edge_name not in valid_edges:
-                raise HTTPException(
-                    status_code=400,
-                    detail=f"Invalid edge '{edge_name}'. Must be one of: {', '.join(valid_edges)}"
-                )
-            if len(color) != 3 or not all(0 <= c <= 255 for c in color):
-                raise HTTPException(
-                    status_code=400,
-                    detail=f"Invalid color for edge '{edge_name}'. Must be [R, G, B] with values 0-255."
-                )
-
-        await manager.set_test_mode(device_id, body.edges)
-
-        active_edges = list(body.edges.keys())
-        logger.info(
-            f"Test mode {'activated' if active_edges else 'deactivated'} "
-            f"for device {device_id}: {active_edges}"
-        )
-
-        return CalibrationTestModeResponse(
-            test_mode=len(active_edges) > 0,
-            active_edges=active_edges,
-            device_id=device_id,
-        )
-
-    except HTTPException:
-        raise
-    except ValueError as e:
-        raise HTTPException(status_code=404, detail=str(e))
-    except Exception as e:
-        logger.error(f"Failed to set test mode: {e}")
-        raise HTTPException(status_code=500, detail=str(e))