Add playidea-lab/pcq to Data Science Tools

Agent-operable ML experiment contract — cq.yaml + JSON contracts +
built-in MCP server exposing 14 tools (resolve_project,
inspect_project, run_experiment, validate_run, describe_run,
compare_runs, lineage_chain, ...) for running, validating, and tracing
experiments across any framework. Apache-2.0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>