harden(hf): pin huggingface_hub<1.0 (gradio 5.50 oauth needs HfFolder, removed in hub 1.0)

fix(hf): gradio 5.50.0 (MCP support; 4.44 had no [mcp] extra) + keep audioop-lts

fix(hf): add audioop-lts for Python 3.13 (gradio/pydub needs the removed audioop module)

DC Hub — Power Index demo + MCP server (real app)