feat: ComfyUI embedded dev setup + proxy auth with downstream keys

- COMFYUI_BASE configurable via env var (default 127.0.0.1:8188)
- All /api/comfyui/ routes protected by downstream API Key or admin token
- docker/Dockerfile.comfyui + docker-compose.comfyui.yml for dev
- npm scripts: comfyui:install, comfyui:start, comfyui:stop
- .gitignore / .env.example updated

docker/Dockerfile.comfyui

@@ -0,0 +1,27 @@
+FROM python:3.11-slim
+
+WORKDIR /workspace
+
+# Install system deps
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    git curl \
+    && rm -rf /var/lib/apt/lists/*
+
+# Clone ComfyUI
+RUN git clone https://github.com/comfyanonymous/ComfyUI.git /workspace/ComfyUI
+
+WORKDIR /workspace/ComfyUI
+
+# Python venv + deps (CPU-only, generation goes through BoosAPI)
+RUN python3 -m venv venv && \
+    . venv/bin/activate && \
+    pip install --upgrade pip && \
+    pip install torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cpu && \
+    grep -v kornia_rs requirements.txt | pip install -r /dev/stdin && \
+    rm -rf ~/.cache/pip
+
+ENV PATH="/workspace/ComfyUI/venv/bin:${PATH}"
+
+EXPOSE 8188
+
+CMD ["python3", "main.py", "--listen", "0.0.0.0", "--port", "8188", "--cpu"]