Configure lefthook formatter checks

[NathanFlurry]

Summary

• add root lefthook and Biome configuration for pre-commit auto-formatting
• run Biome on staged JS/TS/JSON files and rustfmt on staged Rust files
• add a CI formatter check that validates changed formatter-managed files through lefthook

Testing

• pnpm exec lefthook run pre-commit --no-stage-fixed --fail-on-changes --file package.json --file biome.json --file .github/workflows/ci.yaml --file pnpm-lock.yaml --file lefthook.yml

[railway-app]

🚅 Deployed to the sandbox-agent-pr-231 environment in sandbox-agent

Service	Status	Web	Updated (UTC)
website	😴 Sleeping (View Logs)	Web	Mar 11, 2026 at 6:02 am