comfyui: bake qwen_image21 patch into image via startup wrapper

The qwen_image21 detection check and GGUF node arch list patch are
applied by a startup wrapper (comfyui-start.sh) that runs before
ComfyUI starts. The patch script and wrapper are baked into the image
so they survive container recreations. The quadlet's Exec now points
at the wrapper instead of main.py directly.

dankclaw/comfyui-start.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+# Apply qwen_image21 patches before starting ComfyUI
+python3 /opt/ComfyUI/apply_qwen21_patch.py 2>/dev/null
+exec python main.py --listen 0.0.0.0 --port 8188