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/api/schemas/scene_presets.py

@@ -0,0 +1,67 @@
+"""Scene preset API schemas."""
+
+from datetime import datetime
+from typing import List, Optional
+
+from pydantic import BaseModel, Field
+
+
+class TargetSnapshotSchema(BaseModel):
+    target_id: str
+    running: bool = False
+    color_strip_source_id: str = ""
+    brightness_value_source_id: str = ""
+    fps: int = 30
+    auto_start: bool = False
+
+
+class DeviceBrightnessSnapshotSchema(BaseModel):
+    device_id: str
+    software_brightness: int = 255
+
+
+class ProfileSnapshotSchema(BaseModel):
+    profile_id: str
+    enabled: bool = True
+
+
+class ScenePresetCreate(BaseModel):
+    """Create a scene preset by capturing current state."""
+
+    name: str = Field(description="Preset name", min_length=1, max_length=100)
+    description: str = Field(default="", max_length=500)
+    color: str = Field(default="#4fc3f7", description="Card accent color")
+
+
+class ScenePresetUpdate(BaseModel):
+    """Update scene preset metadata (not snapshot data — use recapture for that)."""
+
+    name: Optional[str] = Field(None, min_length=1, max_length=100)
+    description: Optional[str] = Field(None, max_length=500)
+    color: Optional[str] = None
+    order: Optional[int] = None
+
+
+class ScenePresetResponse(BaseModel):
+    """Scene preset with full snapshot data."""
+
+    id: str
+    name: str
+    description: str
+    color: str
+    targets: List[TargetSnapshotSchema]
+    devices: List[DeviceBrightnessSnapshotSchema]
+    profiles: List[ProfileSnapshotSchema]
+    order: int
+    created_at: datetime
+    updated_at: datetime
+
+
+class ScenePresetListResponse(BaseModel):
+    presets: List[ScenePresetResponse]
+    count: int
+
+
+class ActivateResponse(BaseModel):
+    status: str = Field(description="'activated' or 'partial'")
+    errors: List[str] = Field(default_factory=list)