feat: v2.0.0 — Major refactor and node reorganization
## Nodes
- Unified node key prefix to Util* (UtilSwitch, UtilStringToList, etc.)
- Added UtilSaveFile: combined Save Text & Image node with batch/list support,
shared counter, subfolder, INPUT_IS_LIST
- Added UtilJsonToList: JSON file/string to STRING list via dot-notation key
- Added UtilEmptyLatent channels param (16=Flux/Lumina/SD3, 4=SD/SDXL)
- Updated UtilLoadImageList: count-based dropdown selectors from Input folder
- Added CNStepControl, CNPreprocessor (canny/depth/lineart/openpose/mlsd)
- Added ImageCropResize, LoRAStepLoader
- Added SBPromptFilter (Claude API style/controlnet filtering)
- Removed layer_nodes.py, sampler_nodes.py (layer separation experiments)
- Removed experiments/ directory
## Dependencies
- Removed controlnet_aux — direct preprocessor implementations in preprocessors/
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
