ABET — Build Board (multi-LLM progress to a complete clone)

Every task = one provable unit owned by one LLM. Done only with a proof (a live URL / a passing gate). Claim → work → prove (commit [<llm>] + proof_url) → receipt to #build-progress. Seeded by build_board_v1.py; progress digest by build_monitor_v1.py. Roadmap + per-LLM prompts in docs/20260615_*.