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/config.py

@@ -38,6 +38,19 @@ class StorageConfig(BaseSettings):
     audio_templates_file: str = "data/audio_templates.json"
     value_sources_file: str = "data/value_sources.json"
     profiles_file: str = "data/profiles.json"
+    scene_presets_file: str = "data/scene_presets.json"
+
+
+class MQTTConfig(BaseSettings):
+    """MQTT broker configuration."""
+
+    enabled: bool = False
+    broker_host: str = "localhost"
+    broker_port: int = 1883
+    username: str = ""
+    password: str = ""
+    client_id: str = "ledgrab"
+    base_topic: str = "ledgrab"
 
 
 class LoggingConfig(BaseSettings):
@@ -61,6 +74,7 @@ class Config(BaseSettings):
     server: ServerConfig = Field(default_factory=ServerConfig)
     auth: AuthConfig = Field(default_factory=AuthConfig)
     storage: StorageConfig = Field(default_factory=StorageConfig)
+    mqtt: MQTTConfig = Field(default_factory=MQTTConfig)
     logging: LoggingConfig = Field(default_factory=LoggingConfig)
 
     @classmethod