Add profile conditions, scene presets, MQTT integration, and Scenes tab

Feature 1 — Profile Conditions: time-of-day, system idle (Win32
GetLastInputInfo), and display state (GUID_CONSOLE_DISPLAY_STATE)
condition types for automatic profile activation.

Feature 2 — Scene Presets: snapshot/restore system that captures target
running states, device brightness, and profile enables. Server-side
capture with 5-step activation order. Dedicated Scenes tab with
CardSection-based card grid, command palette integration, and dashboard
quick-activate section.

Feature 3 — MQTT Integration: MQTTService singleton with aiomqtt,
MQTTLEDClient device provider for pixel output, MQTT profile condition
type with topic/payload matching, and frontend support for MQTT device
type and condition editor.

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

server/src/wled_controller/core/devices/led_client.py

@@ -282,5 +282,8 @@ def _register_builtin_providers():
     from wled_controller.core.devices.mock_provider import MockDeviceProvider
     register_provider(MockDeviceProvider())
 
+    from wled_controller.core.devices.mqtt_provider import MQTTDeviceProvider
+    register_provider(MQTTDeviceProvider())
+
 
 _register_builtin_providers()

server/src/wled_controller/core/devices/mqtt_client.py

@@ -0,0 +1,98 @@
+"""MQTT LED client — publishes pixel data to an MQTT topic."""
+
+import json
+from typing import List, Optional, Tuple, Union
+
+import numpy as np
+
+from wled_controller.core.devices.led_client import DeviceHealth, LEDClient
+from wled_controller.utils import get_logger
+
+logger = get_logger(__name__)
+
+# Singleton reference — injected from main.py at startup
+_mqtt_service = None
+
+
+def set_mqtt_service(service) -> None:
+    global _mqtt_service
+    _mqtt_service = service
+
+
+def get_mqtt_service():
+    return _mqtt_service
+
+
+def parse_mqtt_url(url: str) -> str:
+    """Extract topic from an mqtt:// URL.
+
+    Format: mqtt://topic/path  (broker connection is global via config)
+    """
+    if url.startswith("mqtt://"):
+        return url[7:]
+    return url
+
+
+class MQTTLEDClient(LEDClient):
+    """Publishes JSON pixel data to an MQTT topic via the shared service."""
+
+    def __init__(self, url: str, led_count: int = 0, **kwargs):
+        self._topic = parse_mqtt_url(url)
+        self._led_count = led_count
+        self._connected = False
+
+    async def connect(self) -> bool:
+        svc = _mqtt_service
+        if svc is None or not svc.is_enabled:
+            raise ConnectionError("MQTT service not available")
+        if not svc.is_connected:
+            raise ConnectionError("MQTT service not connected to broker")
+        self._connected = True
+        return True
+
+    async def close(self) -> None:
+        self._connected = False
+
+    @property
+    def is_connected(self) -> bool:
+        return self._connected and _mqtt_service is not None and _mqtt_service.is_connected
+
+    async def send_pixels(
+        self,
+        pixels: Union[List[Tuple[int, int, int]], np.ndarray],
+        brightness: int = 255,
+    ) -> bool:
+        svc = _mqtt_service
+        if svc is None or not svc.is_connected:
+            return False
+
+        if isinstance(pixels, np.ndarray):
+            pixel_list = pixels.tolist()
+        else:
+            pixel_list = list(pixels)
+
+        payload = json.dumps({
+            "pixels": pixel_list,
+            "brightness": brightness,
+            "led_count": len(pixel_list),
+        })
+
+        await svc.publish(self._topic, payload, retain=False, qos=0)
+        return True
+
+    @classmethod
+    async def check_health(
+        cls,
+        url: str,
+        http_client,
+        prev_health=None,
+    ) -> DeviceHealth:
+        from datetime import datetime
+        svc = _mqtt_service
+        if svc is None or not svc.is_enabled:
+            return DeviceHealth(online=False, error="MQTT disabled", last_checked=datetime.utcnow())
+        return DeviceHealth(
+            online=svc.is_connected,
+            last_checked=datetime.utcnow(),
+            error=None if svc.is_connected else "MQTT broker disconnected",
+        )

server/src/wled_controller/core/devices/mqtt_provider.py

@@ -0,0 +1,51 @@
+"""MQTT device provider — factory, validation, health checks."""
+
+from datetime import datetime
+from typing import List, Optional, Tuple
+
+from wled_controller.core.devices.led_client import (
+    DeviceHealth,
+    DiscoveredDevice,
+    LEDClient,
+    LEDDeviceProvider,
+)
+from wled_controller.core.devices.mqtt_client import (
+    MQTTLEDClient,
+    get_mqtt_service,
+    parse_mqtt_url,
+)
+from wled_controller.utils import get_logger
+
+logger = get_logger(__name__)
+
+
+class MQTTDeviceProvider(LEDDeviceProvider):
+    """Provider for MQTT-based LED devices."""
+
+    @property
+    def device_type(self) -> str:
+        return "mqtt"
+
+    @property
+    def capabilities(self) -> set:
+        return {"manual_led_count"}
+
+    def create_client(self, url: str, **kwargs) -> LEDClient:
+        return MQTTLEDClient(url, **kwargs)
+
+    async def check_health(
+        self, url: str, http_client, prev_health=None,
+    ) -> DeviceHealth:
+        return await MQTTLEDClient.check_health(url, http_client, prev_health)
+
+    async def validate_device(self, url: str) -> dict:
+        """Validate MQTT device URL (topic path)."""
+        topic = parse_mqtt_url(url)
+        if not topic or topic == "/":
+            raise ValueError("MQTT topic cannot be empty")
+        # Can't auto-detect LED count — require manual entry
+        return {}
+
+    async def discover(self, timeout: float = 3.0) -> List[DiscoveredDevice]:
+        # MQTT devices are not auto-discoverable
+        return []