809bccfbe7
The refreshed provider table said 12 embedders; EmbedderFactory registers 11. The other three rows were right, so the table drifted silently again inside the commit that was fixing it drifting. Add tests/test_agents_md_provider_counts.py, which parses the AGENTS.md provider table and asserts each documented count equals len(<Factory>.provider_to_class). Verified it fails on the 12 and passes on 11.