workflow_sample: replace per-task samples with one All-In-One workflow + rewrite README

Single QuantFunc-Sample-WorkFlow-All-In-One.json (34 nodes, v2) demonstrating 3 model-load
methods (existing UNet/CLIP/VAE · base/pre-quantized · all-in-one checkpoint) x t2i / edit /
export. README.md + README_zh.md rewritten for the v2 nodes (Pick*/Build Pipeline/Auto Loaders).
Removed the old Easy-Gen / Text-to-Image / Image-to-Image / Model-Export samples.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>