Rewrite HAOS integration: target-centric architecture with KC color sensors

- Rewrite integration to target-centric model: each picture target becomes
  a HA device under a server hub with switch, FPS, and status sensors
- Replace KC light entities with color sensors (hex state + RGB attributes)
  for better automation support via WebSocket real-time updates
- Add WebSocket manager for Key Colors color streaming
- Add KC per-stage timing metrics (calc_colors, broadcast) with rolling avg
- Fix KC timing fields missing from API by adding them to Pydantic schema
- Make start/stop processing idempotent to prevent intermittent 404 errors
- Add HAOS localization support (en, ru) using translation_key system
- Rename integration from "WLED Screen Controller" to "LED Screen Controller"
- Remove obsolete select.py (display select) and README.md

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

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

@@ -133,6 +133,8 @@ class TargetProcessingState(BaseModel):
     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")
     overlay_active: bool = Field(default=False, description="Whether visualization overlay is active")
     last_update: Optional[datetime] = Field(None, description="Last successful update")