Add versioned compatibility profile registry - #79

Summary

• add a closed typed registry with independently versioned profile identity
• expose torch-free profiles and compat introspection commands
• bind new direct-GKD plans, native runs, caches, checkpoints, and exports to profile identity
• begin the CLI domain split without changing existing commands

Validation

• full non-GPU/non-network suite: 2,254 passed, 10 skipped, 22 deselected; 83.85% branch coverage
• pinned official verl profile smoke passed in CI
• focused registry, plan, cache, checkpoint, export, and materialization tests passed
• ruff check and format check
• mypy across 163 source files
• strict MkDocs build and link/text checks
• wheel/sdist build and twine check
• frozen calculator SHA-256 unchanged: 53fc1d4d5b7adee09618d77ad62d4086ba56b78569832d6fc7c3bcd5c2695bbc

No third-party profile loader, algorithm change, benchmark run, or distributed-execution claim is included.