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/app/models.py

@@ -0,0 +1,34 @@
+# services/comfy-agent/app/models.py
+from pydantic import BaseModel, Field
+from typing import Any, Dict, Optional, Literal
+
+GenType = Literal["text-to-image", "text-to-video", "image-to-video"]
+
+class GenerateImageRequest(BaseModel):
+    prompt: str = Field(min_length=1)
+    negative_prompt: Optional[str] = None
+    width: int = 1024
+    height: int = 1024
+    steps: int = 28
+    seed: Optional[int] = None
+    workflow: Optional[str] = None
+    workflow_params: Dict[str, Any] = Field(default_factory=dict)
+
+class GenerateVideoRequest(BaseModel):
+    prompt: str = Field(min_length=1)
+    seconds: int = 4
+    fps: int = 24
+    steps: int = 30
+    seed: Optional[int] = None
+    workflow: Optional[str] = None
+    workflow_params: Dict[str, Any] = Field(default_factory=dict)
+
+class JobStatus(BaseModel):
+    job_id: str
+    type: GenType
+    status: Literal["queued", "running", "succeeded", "failed"]
+    progress: float = 0.0
+    message: Optional[str] = None
+    result_url: Optional[str] = None
+    error: Optional[str] = None
+    comfy_prompt_id: Optional[str] = None