feat(mcp-image-gen): scaffold ComfyUI-backed image generation MCP server

- FastMCP server with 4 tools: generate_image, list_available_models,
  get_generation_status, get_output_directory
- ComfyUI REST API client (httpx) polling lifecycle
- FLUX.1-schnell workflow JSON template
- Dual output: TextContent (path + seed) + ImageContent (base64 PNG)
- 14 passing pytest tests with respx HTTP mocking
- ROCm/AMD RX 7900 XTX optimized setup in README
- Ollama Linux migration path documented (future)

mcp/mcp-image-gen/src/workflows/flux_schnell.json

@@ -0,0 +1,59 @@
+{
+  "6": {
+    "class_type": "CLIPTextEncode",
+    "inputs": {
+      "clip": ["30", 1],
+      "text": "PROMPT_PLACEHOLDER"
+    }
+  },
+  "8": {
+    "class_type": "VAEDecode",
+    "inputs": {
+      "samples": ["13", 0],
+      "vae": ["30", 2]
+    }
+  },
+  "9": {
+    "class_type": "SaveImage",
+    "inputs": {
+      "filename_prefix": "mcp-image-gen",
+      "images": ["8", 0]
+    }
+  },
+  "13": {
+    "class_type": "KSampler",
+    "inputs": {
+      "cfg": 1.0,
+      "denoise": 1.0,
+      "latent_image": ["27", 0],
+      "model": ["30", 0],
+      "negative": ["33", 0],
+      "positive": ["6", 0],
+      "sampler_name": "euler",
+      "scheduler": "simple",
+      "seed": 42,
+      "steps": 4
+    }
+  },
+  "27": {
+    "class_type": "EmptySD3LatentImage",
+    "inputs": {
+      "batch_size": 1,
+      "height": 1024,
+      "width": 1024
+    }
+  },
+  "30": {
+    "class_type": "CheckpointLoaderSimple",
+    "inputs": {
+      "ckpt_name": "flux1-schnell.safetensors"
+    }
+  },
+  "33": {
+    "class_type": "CLIPTextEncode",
+    "inputs": {
+      "clip": ["30", 1],
+      "text": "NEGATIVE_PLACEHOLDER"
+    }
+  }
+}