Add two WD14 classifier models as alternatives to JoyCaption LLM taggers.
WD14 models are ~400MB ONNX classifiers that output Danbooru tags with
confidence scores — much faster inference, no prompt needed.
Backend:
- Add wd14-swinv2 and wd14-vit entries to MODELS dict
- Add check/download/load/generate methods for ONNX-based WD14 inference
- Add general_threshold and character_threshold params to generate_tags()
- Filter "prepend:*" tags from exclude prefixes and skip-tagged logic
Frontend:
- Add WD14 radio buttons with download status in both admin and gallery
- Toggle prompt textarea vs threshold sliders based on model selection
- Pass thresholds to API for batch and single-image tagging
- Extract _setModelStatus() helper using safe DOM methods
Dependencies: onnxruntime (optional, with clear error message)