feat: add dedicated CivitAI NSFW model downloader

- Add models_civitai.yaml with 6 NSFW SDXL checkpoints
- Create artifact_civitai_download.sh with beautiful purple/magenta CLI
- Update .env.example with CIVITAI_API_KEY documentation
- Update CLAUDE.md with CivitAI usage instructions
- Rename comfyui_models.yaml to models_huggingface.yaml for clarity

Features:
- Dedicated config and downloader for CivitAI models
- Same elegant architecture as HuggingFace downloader
- Retry logic, rate limiting, progress bars
- Models: LUSTIFY, Pony Diffusion V6, RealVisXL, etc.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

CLAUDE.md

@@ -288,6 +288,79 @@ environment=HF_HOME="../huggingface_cache",HF_TOKEN="%(ENV_HF_TOKEN)s"
 supervisorctl start vllm-mistral
 ```
 
+### Downloading NSFW Models from CivitAI
+
+The project includes dedicated tooling for downloading NSFW models from CivitAI, separate from the HuggingFace downloader.
+
+**Files:**
+- Configuration: `models_civitai.yaml` - Defines available CivitAI models
+- Downloader: `artifact_civitai_download.sh` - Beautiful CLI tool for downloading models
+
+**Requirements:**
+- CivitAI API key (set in `.env` file as `CIVITAI_API_KEY`)
+- Get your key from: https://civitai.com/user/account
+
+**Available Models (Essential):**
+1. **LUSTIFY v7.0 GGWP** (6.31GB) - Photoreal NSFW checkpoint for women
+2. **Pony Diffusion V6 XL** (6.5GB) - Anime/furry NSFW with balanced content
+3. **RealVisXL V5.0** (6.8GB) - Photorealistic NSFW model
+
+**Usage:**
+
+```bash
+# Download all essential NSFW models (19.61GB)
+artifact_civitai_download.sh
+
+# Download only (no symlinks)
+artifact_civitai_download.sh download
+
+# Create symlinks only (models already downloaded)
+artifact_civitai_download.sh link
+
+# Custom configuration file
+artifact_civitai_download.sh -c /path/to/models_civitai.yaml
+
+# Help
+artifact_civitai_download.sh --help
+```
+
+**Directory Structure:**
+- Models downloaded to: `/workspace/models/civitai/` (cache)
+- Symlinks created in: `/workspace/ComfyUI/models/checkpoints/`
+
+**Features:**
+- Beautiful purple/magenta themed CLI (vs cyan for HuggingFace)
+- Automatic retry with exponential backoff for rate limiting
+- Resume interrupted downloads
+- Progress bars and status indicators
+- Parallel download support (respects rate limits)
+
+**Configuration Example (`models_civitai.yaml`):**
+
+```yaml
+model_categories:
+  nsfw_checkpoints:
+    - name: lustify-v7-ggwp
+      version_id: "1094291"
+      model_id: "573152"
+      description: "LUSTIFY v7.0 GGWP - Photoreal NSFW checkpoint"
+      size_gb: 6.31
+      essential: true
+      type: checkpoints
+```
+
+**Installation Profiles:**
+- `essential`: 3 models (LUSTIFY, Pony, RealVisXL) - 19.61GB, 30-60 min
+- `complete`: All 6 models - 39.21GB, 1-2 hours
+- `realistic_only`: LUSTIFY + RealVisXL - 13.11GB, 20-40 min
+- `anime_only`: Pony + WAI-NSFW - 13.0GB, 20-40 min
+
+**Important Notes:**
+- All models are SDXL-based (require ~12GB VRAM)
+- Cannot run simultaneously with FLUX models (both use ~23GB)
+- Can run with smaller models like standard SDXL (~12GB total)
+- Rate limiting: 5 second delay between downloads (configurable)
+
 ## Key Implementation Details
 
 ### Direct vLLM Server Architecture