chore: split quality check scripts

[mastro993]

Summary

• split frontend and backend format, lint, test, and check scripts at the workspace root
• keep CI frontend/backend checks in separate parallel jobs
• add an advisory PostToolUse quality hook that auto-fixes changed frontend and Rust files, then verifies them
• add focused dispatcher and Tauri dist preparation tests
• update README and Lefthook command references

Validation

• pnpm check
• pnpm test
• pnpm test:hooks
• frontend format and lint checks
• Rust Clippy and workspace tests