feat: integrate ACE Step music generation with 19-language support

Added ACE Step v1 3.5B model for state-of-the-art music generation:
- 15x faster than LLM baselines with superior structural coherence
- Supports 19 languages (en, zh, ja, ko, fr, es, de, it, pt, ru + 9 more)
- Voice cloning, lyric alignment, and multi-genre capabilities

Changes:
- Added ACE Step models to models_huggingface.yaml (checkpoint + Chinese RAP LoRA)
- Added ComfyUI_ACE-Step custom node to arty.yml with installation script
- Created 4 comprehensive workflows in comfyui/workflows/text-to-music/:
  * acestep-simple-t2m-v1.json - Basic 60s text-to-music generation
  * acestep-multilang-t2m-v1.json - 19-language music generation
  * acestep-remix-m2m-v1.json - Music-to-music remixing with style transfer
  * acestep-chinese-rap-v1.json - Chinese hip-hop with specialized LoRA

🤖 Generated with Claude Code (https://claude.com/claude-code)

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

arty.yml

@@ -68,6 +68,11 @@ references:
     description: "DiffRhythm - Full-length song generation (up to 4m45s) with text/audio conditioning"
     essential: false
 
+  - url: https://github.com/billwuhao/ComfyUI_ACE-Step.git
+    into: $COMFYUI_ROOT/custom_nodes/ComfyUI_ACE-Step
+    description: "ACE Step - State-of-the-art music generation with 19-language support, voice cloning, and superior coherence"
+    essential: false
+
   - url: https://github.com/ssitu/ComfyUI_UltimateSDUpscale.git
     into: $COMFYUI_ROOT/custom_nodes/ComfyUI_UltimateSDUpscale
     description: "Ultimate SD Upscale for high-quality image upscaling"
@@ -368,6 +373,35 @@ scripts:
       exit 1
     fi
 
+  setup/comfyui-acestep: |
+    echo "========================================="
+    echo "  Installing ACE Step Custom Node"
+    echo "========================================="
+    echo ""
+
+    cd $COMFYUI_ROOT/custom_nodes
+
+    # Clone repository if not exists
+    if [ ! -d "ComfyUI_ACE-Step" ]; then
+      echo "Cloning ComfyUI_ACE-Step repository..."
+      git clone https://github.com/billwuhao/ComfyUI_ACE-Step.git
+    else
+      echo "ComfyUI_ACE-Step already exists, skipping clone"
+    fi
+
+    # Install dependencies in ComfyUI venv
+    echo ""
+    echo "Installing ACE Step dependencies..."
+    cd $COMFYUI_ROOT
+    source venv/bin/activate
+    pip install -r custom_nodes/ComfyUI_ACE-Step/requirements.txt
+    deactivate
+
+    echo ""
+    echo "✓ ACE Step custom node installed successfully"
+    echo "  Note: Download models separately using:"
+    echo "  bash /workspace/bin/artifact_huggingface_download.sh download -c models_huggingface.yaml --category audio_models"
+
   setup/pivoine-nodes: |
     echo "========================================="
     echo "  Linking Pivoine Custom Nodes"