🔧 Chore Summary

Add cargo-shear to Rust CI so unused dependencies fail fast, and remove or reclassify the unused crate entries detected by the new check.

🧱 Area Affected

Choose the general area(s) that this chore affects:

• GitHub Actions / CI Pipelines
• Pre-commit hooks / linters
• Formatting (black, isort, ruff, etc.)
• Type-checking (mypy, pyright, pytype, etc.)
• Dependency cleanup or updates
• Build system or Makefile
• Containerization (Docker/Podman)
• Docs or spellcheck
• SBOM, CVE scans, licenses, or security checks
• Other:

⚙️ Context / Rationale

Rust manifests can accumulate stale dependencies that increase review noise, compile surface, and maintenance overhead. A CI check keeps dependency hygiene enforceable across the workspace.

📦 Related Make Targets

• make rust-unused-deps - run cargo-shear across the Rust workspace
• make rust-check - include the unused dependency check with the existing Rust checks

📋 Acceptance Criteria

• cargo-shear runs in Rust CI
• Unused Rust dependencies are removed or moved to the correct manifest section
• Rust checks pass with no dependency usage warnings

🧩 Additional Context

Use cargo-shear 1.13.1 with --locked --deny-warnings so CI uses the lockfile and treats dependency hygiene findings as failures.