Add nano-string-utils to String section

[Zheruel]

Checklist:

• I've read and understood Contributing Guidelines.
• I've added the new resource at the end of its section.
• This resource is out there for a while, and actively maintained.
• This resource is popular enough and has at least a few hundred stars on GitHub.

---

About nano-string-utils

I'm adding nano-string-utils to the String section. This is an ultra-lightweight string utilities library with the following key features:

• Zero dependencies - No supply chain vulnerabilities or bloat
• Tree-shakeable - Each function is independently importable with minimal overhead (< 1KB per function)
• Fully typed - Complete TypeScript support with template literal types and branded types
• 48 utility functions - Comprehensive string manipulation, validation, and transformation functions
• Production ready - 100% test coverage, actively maintained with CI/CD
• Modern - Built for ES2022+ with ESM and CJS support
• Fast - Competitive performance with popular alternatives like lodash and es-toolkit

The library has been actively maintained since its release and provides a modern, dependency-free alternative to libraries like lodash/underscore.string with excellent bundle size characteristics.

GitHub: https://github.com/Zheruel/nano-string-utils
NPM: https://www.npmjs.com/package/nano-string-utils
JSR: https://jsr.io/@zheruel/nano-string-utils