feat: make Cargo crate caching sound via lockfile + toolchain hashing
Add the workspace Cargo.lock and pinned rust-toolchain files to every Cargo
crate task as hashed inputs (relative to the crate via path_to_root), keeping
default package-file hashing on so source changes still invalidate. This
makes the cache sound across dependency and toolchain changes, not just
source changes.
Verified on this repo for turborepo-unescape: editing Cargo.lock,
rust-toolchain.toml, or crate source each produces a cache miss; reverting
restores the original hash and a cache hit.
Note: an unpinned (PATH) rustc is not folded into the hash; pinning via
rust-toolchain.toml (as this repo does) is the supported path.
https://claude.ai/code/session_014BEtoj4wxFHGipkRgJUBxi