feat: add Prequant and PrecisionConfig auto loader nodes, remove scheduler_config from AutoLoader

- Remove scheduler_config input from QuantFuncModelAutoLoader (kept in ModelLoader)
- Add QuantFuncPrequantAutoLoader node: auto-download prequant weights from ModelScope/HuggingFace, outputs STRING connectable to ModelLoader
- Add QuantFuncPrecisionConfigAutoLoader node: auto-download precision config from ModelScope/HuggingFace, outputs STRING connectable to ModelLoader
- Add resolve_selection_no_series() for parsing dropdown selection without requiring model_series input

Co-Authored-By: QuantFunc <noreply@quantfunc.com>