Add audio sources as first-class entities, add mapped CSS type, simplify target editor for mapped sources

- Audio sources moved to separate tab with dedicated CRUD API, store, and editor modal
- New "mapped" color strip source type: assigns different CSS sources to distinct LED sub-ranges (zones)
- Mapped stream runtime with per-zone sub-streams, auto-sizing, hot-update support
- Target editor auto-collapses segments UI when mapped CSS is selected
- Delete protection for CSS sources referenced by mapped zones
- Compact header/footer layout

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

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

@@ -0,0 +1,53 @@
+"""Audio source schemas (CRUD)."""
+
+from datetime import datetime
+from typing import List, Literal, Optional
+
+from pydantic import BaseModel, Field
+
+
+class AudioSourceCreate(BaseModel):
+    """Request to create an audio source."""
+
+    name: str = Field(description="Source name", min_length=1, max_length=100)
+    source_type: Literal["multichannel", "mono"] = Field(description="Source type")
+    # multichannel fields
+    device_index: Optional[int] = Field(None, description="Audio device index (-1 = default)")
+    is_loopback: Optional[bool] = Field(None, description="True for system audio (WASAPI loopback)")
+    # mono fields
+    audio_source_id: Optional[str] = Field(None, description="Parent multichannel audio source ID")
+    channel: Optional[str] = Field(None, description="Channel: mono|left|right")
+    description: Optional[str] = Field(None, description="Optional description", max_length=500)
+
+
+class AudioSourceUpdate(BaseModel):
+    """Request to update an audio source."""
+
+    name: Optional[str] = Field(None, description="Source name", min_length=1, max_length=100)
+    device_index: Optional[int] = Field(None, description="Audio device index (-1 = default)")
+    is_loopback: Optional[bool] = Field(None, description="True for system audio (WASAPI loopback)")
+    audio_source_id: Optional[str] = Field(None, description="Parent multichannel audio source ID")
+    channel: Optional[str] = Field(None, description="Channel: mono|left|right")
+    description: Optional[str] = Field(None, description="Optional description", max_length=500)
+
+
+class AudioSourceResponse(BaseModel):
+    """Audio source response."""
+
+    id: str = Field(description="Source ID")
+    name: str = Field(description="Source name")
+    source_type: str = Field(description="Source type: multichannel or mono")
+    device_index: Optional[int] = Field(None, description="Audio device index")
+    is_loopback: Optional[bool] = Field(None, description="WASAPI loopback mode")
+    audio_source_id: Optional[str] = Field(None, description="Parent multichannel source ID")
+    channel: Optional[str] = Field(None, description="Channel: mono|left|right")
+    description: Optional[str] = Field(None, description="Description")
+    created_at: datetime = Field(description="Creation timestamp")
+    updated_at: datetime = Field(description="Last update timestamp")
+
+
+class AudioSourceListResponse(BaseModel):
+    """List of audio sources."""
+
+    sources: List[AudioSourceResponse] = Field(description="List of audio sources")
+    count: int = Field(description="Number of sources")