Replace `[lints] workspace = true` with explicit lint configuration in
each crate's Cargo.toml. This allows nix-cargo-integration to build
individual crates in isolation, as it cannot resolve workspace-level
lint configuration when building crates independently.
The previous "See underlying function" text didn't provide a way to
find the underlying function, forcing users to search the codebase.
Stating the safety contracts explicitly makes the API usable.