fix: replace wait-for-it with cross-platform curl polling in setup-comfyui-server

The wait-for-it Python package uses signal.SIGALRM which is not available
on Windows, causing QA CI to fail on windows-latest runners. Replace with
a portable curl-based polling loop that works on all platforms.

Also remove the wait-for-it pip dependency.

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

.github/actions/setup-comfyui-server/action.yaml

@@ -44,7 +44,6 @@ runs:
         python -m pip install --upgrade pip
         pip install torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cpu
         pip install -r requirements.txt
-        pip install wait-for-it
 
     - name: Start ComfyUI server
       if: ${{ inputs.launch_server == 'true' }}
@@ -52,4 +51,8 @@ runs:
       working-directory: ComfyUI
       run: |
         python main.py --cpu --multi-user --front-end-root ../dist ${{ inputs.extra_server_params }} &
-        wait-for-it --service 127.0.0.1:8188 -t 600
+        for i in $(seq 1 300); do
+          curl -sf http://127.0.0.1:8188/api/system_stats >/dev/null 2>&1 && echo "Server ready" && exit 0
+          sleep 2
+        done
+        echo "::error::ComfyUI server did not start within 600s" && exit 1