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/schemas/picture_targets.py

@@ -1,26 +1,11 @@
-"""Picture target schemas (CRUD, processing state, settings, metrics)."""
+"""Picture target schemas (CRUD, processing state, metrics)."""
 
 from datetime import datetime
-from typing import Dict, List, Literal, Optional
+from typing import Dict, List, Optional
 
 from pydantic import BaseModel, Field
 
-from wled_controller.core.processing.processing_settings import DEFAULT_STATE_CHECK_INTERVAL
-
-
-class ProcessingSettings(BaseModel):
-    """Processing settings for a picture target."""
-
-    display_index: int = Field(default=0, description="Display to capture", ge=0)
-    fps: int = Field(default=30, description="Target frames per second", ge=10, le=90)
-    interpolation_mode: str = Field(default="average", description="LED color interpolation mode (average, median, dominant)")
-    brightness: float = Field(default=1.0, description="Global brightness (0.0-1.0)", ge=0.0, le=1.0)
-    smoothing: float = Field(default=0.3, description="Temporal smoothing factor (0.0=none, 1.0=full)", ge=0.0, le=1.0)
-    standby_interval: float = Field(default=1.0, description="Seconds between keepalive sends when screen is static (0.5-5.0)", ge=0.5, le=5.0)
-    state_check_interval: int = Field(
-        default=DEFAULT_STATE_CHECK_INTERVAL, ge=5, le=600,
-        description="Seconds between WLED health checks"
-    )
+DEFAULT_STATE_CHECK_INTERVAL = 30  # seconds between health checks
 
 
 class KeyColorRectangleSchema(BaseModel):
@@ -65,9 +50,13 @@ class PictureTargetCreate(BaseModel):
 
     name: str = Field(description="Target name", min_length=1, max_length=100)
     target_type: str = Field(default="led", description="Target type (led, key_colors)")
+    # LED target fields
     device_id: str = Field(default="", description="LED device ID")
-    picture_source_id: str = Field(default="", description="Picture source ID")
-    settings: Optional[ProcessingSettings] = Field(None, description="Processing settings (for wled targets)")
+    color_strip_source_id: str = Field(default="", description="Color strip source ID")
+    standby_interval: float = Field(default=1.0, description="Keepalive send interval when screen is static (0.5-5.0s)", ge=0.5, le=5.0)
+    state_check_interval: int = Field(default=DEFAULT_STATE_CHECK_INTERVAL, description="Device health check interval (5-600s)", ge=5, le=600)
+    # KC target fields
+    picture_source_id: str = Field(default="", description="Picture source ID (for key_colors targets)")
     key_colors_settings: Optional[KeyColorsSettingsSchema] = Field(None, description="Key colors settings (for key_colors targets)")
     description: Optional[str] = Field(None, description="Optional description", max_length=500)
 
@@ -76,9 +65,13 @@ class PictureTargetUpdate(BaseModel):
     """Request to update a picture target."""
 
     name: Optional[str] = Field(None, description="Target name", min_length=1, max_length=100)
-    device_id: Optional[str] = Field(None, description="WLED device ID")
-    picture_source_id: Optional[str] = Field(None, description="Picture source ID")
-    settings: Optional[ProcessingSettings] = Field(None, description="Processing settings (for wled targets)")
+    # LED target fields
+    device_id: Optional[str] = Field(None, description="LED device ID")
+    color_strip_source_id: Optional[str] = Field(None, description="Color strip source ID")
+    standby_interval: Optional[float] = Field(None, description="Keepalive interval (0.5-5.0s)", ge=0.5, le=5.0)
+    state_check_interval: Optional[int] = Field(None, description="Health check interval (5-600s)", ge=5, le=600)
+    # KC target fields
+    picture_source_id: Optional[str] = Field(None, description="Picture source ID (for key_colors targets)")
     key_colors_settings: Optional[KeyColorsSettingsSchema] = Field(None, description="Key colors settings (for key_colors targets)")
     description: Optional[str] = Field(None, description="Optional description", max_length=500)
 
@@ -89,10 +82,14 @@ class PictureTargetResponse(BaseModel):
     id: str = Field(description="Target ID")
     name: str = Field(description="Target name")
     target_type: str = Field(description="Target type")
-    device_id: str = Field(default="", description="WLED device ID")
-    picture_source_id: str = Field(default="", description="Picture source ID")
-    settings: Optional[ProcessingSettings] = Field(None, description="Processing settings (wled)")
-    key_colors_settings: Optional[KeyColorsSettingsSchema] = Field(None, description="Key colors settings (key_colors)")
+    # LED target fields
+    device_id: str = Field(default="", description="LED device ID")
+    color_strip_source_id: str = Field(default="", description="Color strip source ID")
+    standby_interval: float = Field(default=1.0, description="Keepalive interval (s)")
+    state_check_interval: int = Field(default=DEFAULT_STATE_CHECK_INTERVAL, description="Health check interval (s)")
+    # KC target fields
+    picture_source_id: str = Field(default="", description="Picture source ID (key_colors)")
+    key_colors_settings: Optional[KeyColorsSettingsSchema] = Field(None, description="Key colors settings")
     description: Optional[str] = Field(None, description="Description")
     created_at: datetime = Field(description="Creation timestamp")
     updated_at: datetime = Field(description="Last update timestamp")
@@ -110,21 +107,18 @@ class TargetProcessingState(BaseModel):
 
     target_id: str = Field(description="Target ID")
     device_id: Optional[str] = Field(None, description="Device ID")
+    color_strip_source_id: Optional[str] = Field(None, description="Color strip source ID")
     processing: bool = Field(description="Whether processing is active")
     fps_actual: Optional[float] = Field(None, description="Actual FPS achieved")
     fps_potential: Optional[float] = Field(None, description="Potential FPS (processing speed without throttle)")
-    fps_target: int = Field(default=0, description="Target FPS")
+    fps_target: Optional[int] = Field(None, description="Target FPS")
     frames_skipped: Optional[int] = Field(None, description="Frames skipped (no screen change)")
     frames_keepalive: Optional[int] = Field(None, description="Keepalive frames sent during standby")
     fps_current: Optional[int] = Field(None, description="Frames sent in the last second")
-    timing_extract_ms: Optional[float] = Field(None, description="Border extraction time (ms)")
-    timing_map_leds_ms: Optional[float] = Field(None, description="LED mapping time (ms)")
-    timing_smooth_ms: Optional[float] = Field(None, description="Smoothing time (ms)")
     timing_send_ms: Optional[float] = Field(None, description="DDP send time (ms)")
-    timing_total_ms: Optional[float] = Field(None, description="Total processing time (ms)")
     timing_calc_colors_ms: Optional[float] = Field(None, description="Color calculation time (ms, KC targets)")
     timing_broadcast_ms: Optional[float] = Field(None, description="WebSocket broadcast time (ms, KC targets)")
-    display_index: int = Field(default=0, description="Current display index")
+    display_index: Optional[int] = Field(None, description="Current display index")
     overlay_active: bool = Field(default=False, description="Whether visualization overlay is active")
     last_update: Optional[datetime] = Field(None, description="Last successful update")
     errors: List[str] = Field(default_factory=list, description="Recent errors")
@@ -147,7 +141,7 @@ class TargetMetricsResponse(BaseModel):
     device_id: Optional[str] = Field(None, description="Device ID")
     processing: bool = Field(description="Whether processing is active")
     fps_actual: Optional[float] = Field(None, description="Actual FPS")
-    fps_target: int = Field(description="Target FPS")
+    fps_target: Optional[int] = Field(None, description="Target FPS")
     uptime_seconds: float = Field(description="Processing uptime in seconds")
     frames_processed: int = Field(description="Total frames processed")
     errors_count: int = Field(description="Total error count")