feat: initial ComfyUI workflow templates extension

- 40 workflow templates (text-to-image, image-to-video, image-to-image,
  text-to-music, upscaling, advanced, nsfw)
- Color-coded placeholder preview images using Pillow
- Template-only extension (no custom nodes)
- Preview generation script for future workflow additions

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

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

__init__.py

@@ -0,0 +1,12 @@
+"""
+ComfyUI Extras - Workflow Templates
+
+A collection of production-ready workflow templates for ComfyUI.
+Templates are automatically discovered from the example_workflows/ directory.
+"""
+
+from .nodes import NODE_CLASS_MAPPINGS, NODE_DISPLAY_NAME_MAPPINGS
+
+__all__ = ['NODE_CLASS_MAPPINGS', 'NODE_DISPLAY_NAME_MAPPINGS']
+
+__version__ = "0.1.0"