feat: Add Comfy Agent service for NODE3 image/video generation

- Create comfy-agent service with FastAPI + NATS integration
- ComfyUI client with HTTP/WebSocket support
- REST API: /generate/image, /generate/video, /status, /result
- NATS subjects: agent.invoke.comfy, comfy.request.*
- Async job queue with progress tracking
- Docker compose configuration for NODE3
- Update PROJECT-MASTER-INDEX.md with NODE2/NODE3 docs

Co-Authored-By: Warp <agent@warp.dev>

services/comfy-agent/Dockerfile

@@ -0,0 +1,13 @@
+# services/comfy-agent/Dockerfile
+FROM python:3.11-slim
+
+WORKDIR /app
+COPY requirements.txt /app/requirements.txt
+RUN pip install --no-cache-dir -r /app/requirements.txt
+
+COPY app /app/app
+
+ENV PYTHONUNBUFFERED=1
+EXPOSE 8880
+
+CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8880"]