feat(posts): add ytx .NET global tool tutorial blog post

Add comprehensive tutorial about building ytx, a YouTube transcript extractor
as a .NET Global Tool. Covers architecture, implementation, CI/CD, and NuGet
publishing following established blog style with emojis and code examples.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: solrevdev