Remove idle color feature, simplify power to turn-off only, fix settings serial port bug

- Remove static/idle color from entire stack (storage, API, processing, UI, CSS, locales)
- Simplify device power button to turn-off only (send black frame, no toggle)
- Send black frame on serial port close (AdalightClient.close)
- Fix settings modal serial port dropdown showing WLED devices due to stale deviceType

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

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

@@ -28,15 +28,6 @@ class DeviceUpdate(BaseModel):
     auto_shutdown: Optional[bool] = Field(None, description="Turn off device when server stops")
 
 
-class StaticColorUpdate(BaseModel):
-    """Request to set or clear the static idle color."""
-
-    color: Optional[List[int]] = Field(
-        None,
-        description="RGB color [R, G, B] with values 0-255, or null to clear",
-    )
-
-
 class Calibration(BaseModel):
     """Calibration configuration for pixel-to-LED mapping."""
 
@@ -102,7 +93,6 @@ class DeviceResponse(BaseModel):
     enabled: bool = Field(description="Whether device is enabled")
     baud_rate: Optional[int] = Field(None, description="Serial baud rate")
     auto_shutdown: bool = Field(default=False, description="Restore device to idle state when targets stop")
-    static_color: Optional[List[int]] = Field(None, description="Static idle color [R, G, B]")
     capabilities: List[str] = Field(default_factory=list, description="Device type capabilities")
     created_at: datetime = Field(description="Creation timestamp")
     updated_at: datetime = Field(description="Last update timestamp")