vanta-migrate — import foreign version files into a Vanta [tools] set.
Reads the common version files (.tool-versions, .nvmrc, .python-version,
rust-toolchain.toml, …) and produces tool→version pairs plus the source they
came from, which the CLI renders into a vanta.toml. See docs/30-migration.md.
Pure-std parsing; no foreign tool is invoked.