refactor: reorganize directory structure and remove hardcoded paths

Move comfyui and vllm out of models/ directory to top level for better
organization. Replace all hardcoded /workspace paths with relative paths
to make the configuration portable across different environments.

Changes:
- Move models/comfyui/ → comfyui/
- Move models/vllm/ → vllm/
- Remove models/ directory (empty)
- Update arty.yml: replace /workspace with environment variables
- Update supervisord.conf: use relative paths from /workspace/ai
- Update all script references to use new paths
- Maintain TQDM_DISABLE=1 to fix BrokenPipeError

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

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

comfyui/start.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+#
+# ComfyUI Startup Script
+# Starts ComfyUI server on port 8188
+#
+
+WORKSPACE_DIR="${WORKSPACE_DIR:-/workspace}"
+COMFYUI_DIR="${WORKSPACE_DIR}/ComfyUI"
+HF_CACHE="${WORKSPACE_DIR}/huggingface_cache"
+
+# Set environment variables
+export PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True
+export HF_HOME="${HF_CACHE}"
+
+# Navigate to ComfyUI directory
+cd "${COMFYUI_DIR}" || exit 1
+
+echo "Starting ComfyUI on port 8188..."
+echo "Access at: http://localhost:8188"
+echo "Using HuggingFace cache: ${HF_CACHE}"
+
+# Start ComfyUI with GPU support
+python3 main.py \
+  --listen 0.0.0.0 \
+  --port 8188 \
+  --enable-cors-header \
+  --preview-method auto
+
+echo "ComfyUI stopped"