Summary

Replaces the sade dependency with Node.js built-in parseArgs from node:util, allowing us to drop multiple dependencies (sade and mri) from svelte-check.

Changes

• Switch from sade to Node.js built-in parseArgs
• Update minimum Node.js version to 18.3.0 (when parseArgs was added)
• Remove sade and @types/sade dependencies
• Maintain full CLI compatibility with existing behavior

Breaking Change

This bumps the minimum Node.js version from 18.0.0 to 18.3.0, but enables dropping external dependencies in favor of built-in functionality.

Fixes #2521