Improve CI/CD pipelines with modern tooling and security best practices

[Makanz]

• Migrate from npm to pnpm with frozen lockfile for reproducible builds
• Add dependency caching to speed up workflow runs
• Update to Node.js 24 (latest LTS)
• Add test execution before npm publishing (critical safety check)
• Add build verification in test workflow
• Implement concurrency control to prevent duplicate runs
• Add explicit permissions (security best practice)
• Enable npm provenance for supply chain security
• Update all actions to latest versions (setup-node@v4)
• Add pnpm/action-setup@v4 for proper pnpm support

Breaking changes prevented: Tests now run before releases to catch issues early.