feat: add comprehensive negative embeddings support (SD 1.5, SDXL, Pony)

- Add 3 new embedding categories to models_civitai.yaml:
  - embeddings_sd15: 6 embeddings (BadDream, UnrealisticDream, badhandv4, EasyNegative, FastNegativeV2, BadNegAnatomyV1-neg)
  - embeddings_sdxl: 1 embedding (BadX v1.1)
  - embeddings_pony: 2 embeddings (zPDXL3, zPDXLxxx)
- Total storage: ~1.1 MB (9 embeddings)
- Add comprehensive embeddings documentation to NSFW README
- Include usage examples, compatibility notes, and syntax guide
- Document embedding weights and recommended combinations

comfyui/workflows/nsfw/README.md

@@ -260,6 +260,98 @@ Use `nsfw-ultimate-upscale-production-v1.json` for professional 2x upscaling wit
 ### Style Transfer:
 Use IP-Adapter workflows in `../image-to-image/` directory to combine with style references.
 
+## Using Negative Embeddings
+
+Negative embeddings (textual inversions) are small trained models that significantly improve image quality when used in negative prompts. They help avoid common artifacts like bad anatomy, unrealistic features, and low-quality outputs.
+
+### Available Embeddings
+
+**For SDXL Models (LUSTIFY, RealVisXL):**
+- `BadX` - Fixes facial/hand artifacts, improves overall realism
+
+**For Pony/WAI-Illustrious Models:**
+- `zPDXL3` - Quality enhancement + removes censoring
+- `zPDXLxxx` - Enables explicit NSFW content
+
+**For SD 1.5 Models (future workflows):**
+- `BadDream` + `UnrealisticDream` - Dreamshaper artifacts + realism
+- `badhandv4` - Improves hand details
+- `FastNegativeV2` - General quality enhancement
+- `BadNegAnatomyV1-neg` - Better anatomy and body joints
+- `easynegative` - General-purpose quality
+
+### Installation
+
+Embeddings are automatically downloaded and linked to `/workspace/ComfyUI/models/embeddings/` when you run:
+
+```bash
+cd /workspace/ai && bash /workspace/bin/artifact_civitai_download.sh both -c models_civitai.yaml
+```
+
+### Usage Syntax
+
+**Basic usage in negative prompt:**
+```
+embedding:BadX
+embedding:zPDXL3
+```
+
+**Multiple embeddings:**
+```
+embedding:zPDXL3, embedding:zPDXLxxx, score_4, score_5, low quality
+```
+
+**With weight adjustment:**
+```
+(embedding:zPDXL3:1.5), (embedding:BadX.pt:1.2), ugly, deformed
+```
+
+**Note:** When using weights, include the full filename with extension (.pt or .safetensors).
+
+### Recommended Usage by Workflow
+
+**LUSTIFY Realistic T2I:**
+```
+Negative: embedding:BadX, (worst quality, low quality:1.4), bad anatomy, deformed, blurry, watermark, text
+```
+
+**RealVisXL Lightning T2I:**
+```
+Negative: embedding:BadX, (worst quality, low quality:1.4), ugly, cartoon, anime
+```
+
+**Pony Anime / WAI-Illustrious T2I:**
+```
+Negative: embedding:zPDXL3, embedding:zPDXLxxx, score_4, score_5, score_6, bad anatomy, deformed
+```
+
+Or with custom strength:
+```
+Negative: (embedding:zPDXL3:1.5), (embedding:zPDXLxxx:1.2), score_4, score_5, low quality
+```
+
+**NSFW Ultimate SD Upscale:**
+```
+Negative: embedding:BadX, (worst quality, low quality:1.4), blurry, pixelated, jpeg artifacts
+```
+
+### Important Compatibility Notes
+
+**CRITICAL:** SD 1.5 embeddings (BadDream, badhandv4, etc.) DO NOT work with SDXL models due to different CLIP architectures. Always use:
+- **SDXL models** → `BadX` embedding
+- **Pony models** → `zPDXL3` and `zPDXLxxx` embeddings
+- **SD 1.5 models** → SD 1.5 embeddings only
+
+Using the wrong embedding type will cause errors or unexpected results.
+
+### Tips
+
+- Start with recommended strength 1.0-2.0 for Pony embeddings
+- `zPDXL3` removes censoring, ideal for NSFW Pony workflows
+- Combine multiple embeddings for best results
+- `BadX` works with all general SDXL checkpoints (LUSTIFY, RealVisXL, etc.)
+- Higher CFG scales (≥11) work better with `badhandv4` (SD 1.5)
+
 ## Notes
 
 - All workflows follow production naming standards