The Rust crate layout expects formatting to run from the rust directory, so add a root-level wrapper that preserves the working command while forwarding user flags like --check. Documentation now points contributors at the wrapper instead of the misleading virtual-workspace manifest invocation.
Constraint: Root-level cargo fmt --manifest-path rust/Cargo.toml is misleading for this virtual workspace
Rejected: Document cd rust && cargo fmt directly | a root wrapper gives one stable repo-root command
Confidence: high
Scope-risk: narrow
Tested: scripts/fmt.sh --check
Tested: git diff --check
