llman-core: the foundation utility layer of llman.
Members: fs_utils / path_utils / managed_block / env_safety /
git_utils / schema_utils. These modules MUST NOT import llman feature
modules (sdd/skills/tool/x) — the direction is locked by
tests/import_direction_tests.rs on the facade side.
The facade crate (llman) re-exports every member at its historical
path (llman::fs_utils, crate::fs_utils, …), so importing code does
not drift when this crate was split out (change src-cleanup-pre-split T11).