The repository had no supply-chain auditing — no deny.toml and no CI
job to catch vulnerable, unmaintained, wrongly-licensed, or
unexpectedly-sourced dependencies.
Add deny.toml covering advisories, bans, licenses and sources:
- licenses: an allow-list of the permissive licenses the dependency
tree actually uses, plus the workspace's own PolyForm-Noncommercial
license and a scoped LLVM-exception for target-lexicon.
- bans: warn on duplicate versions, deny external wildcard deps
(internal path deps are allowed).
- sources: only crates.io.
- advisories: RUSTSEC-2025-0020 (pyo3 0.22) is ignored with a documented
reason — it is reachable only through bindings/python and the pyo3
upgrade is tracked separately; the published crates do not use pyo3.
Add a `supply-chain` CI job running cargo-deny-action (SHA-pinned).
`cargo deny check` passes locally: advisories/bans/licenses/sources ok.
