Document Rust formatting wrapper

Make scripts/fmt.sh robust to caller cwd and document it as the supported repo-root formatting entrypoint for the Rust workspace.

Author: Yeachan-Heo

rust/CLAUDE.md

@@ -7,7 +7,8 @@ This file provides guidance to Claw Code (clawcode.dev) when working with code i
 - Frameworks: none detected from the supported starter markers.
 
 ## Verification
-- Run Rust verification from the repo root: `cargo fmt`, `cargo clippy --workspace --all-targets -- -D warnings`, `cargo test --workspace`
+- From the repository root, run Rust formatting with `scripts/fmt.sh` (or `scripts/fmt.sh --check` for CI-style checks). From this `rust/` directory, the equivalent command is `../scripts/fmt.sh`. Root-level `cargo fmt --manifest-path rust/Cargo.toml` is not the supported formatting command.
+- From this `rust/` directory, run Rust verification with `cargo clippy --workspace --all-targets -- -D warnings` and `cargo test --workspace`.
 
 ## Working agreement
 - Prefer small, reviewable changes and keep generated bootstrap files aligned with actual repo workflows.