Add nullmock to the list of mocking tools

[modoldern]

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.

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Hi! I'd like to suggest nullmock for the list.

While it is a relatively new release and doesn't have hundreds of stars yet (hence the unchecked box above), I believe it brings a highly unique and much-needed approach to the ecosystem that developers will love.

It is a zero-dependency, ultra-fast dynamic API mocking and network simulation server. Unlike traditional tools that require writing complex routes and scripts, nullmock introduces:

1. Next.js-like folder-based dynamic routing (e.g., mocks/users/[id]/GET.json).
2. Smart data generation using magic strings with native i18n support (e.g., {{firstName:tr}}, {{number:10-500}}).
3. Zero-code network simulation via URL parameters (?_delay=2000&_status=404).

It's fully tested, documented, and actively maintained. I hope you consider this a valuable and innovative addition to this awesome list!