fix(deploy): switch to apple-silicon ace-step fork — no nano-vllm, looser gradio pin

fix(deploy): align gradio to ace-step's pin (6.2.0) — drop our own pin, let hf inject

fix(deploy): pin python_version 3.11 — hf spaces base bumped to 3.13 which breaks ace-step pin

fix(deploy): trim README short_description to fit HF Spaces 60-char cap

feat(deploy): preload all hub models + warm demucs on spaces

feat(deploy): m7 — hf spaces readme + cache bootstrap + zerogpu decorator

fix(pipeline): correct hf model id to acestep-v15-xl-sft

docs: add readme with hf space frontmatter and quick start