Add FoldForge module host

[jgassens]

Summary

• Add the FoldForge module host contracts, typed registries, failure-tolerant discovery, and built-in example module.
• Add foldforge modules list/info inspection commands plus module-host tests.
• Keep this PR limited to the host substrate; no symmetry/graft science code or new scientific dependencies.

Verification

• uv run pytest tests/test_module_discovery.py tests/test_module_registry.py tests/test_modules_cli.py -q
• uv run pytest
• uv run ruff check .
• uv run ruff format --check .
• uv run mypy src