feat(blog): Added blogpost for ZEvent2025

[Proxyfil]

This pull request introduces a new blog post and improves the clarity of an existing tutorial. The most notable change is the addition of a comprehensive post detailing technical challenges and solutions encountered during the ZEvent 2025 charity event, with a focus on scaling, resilience, and technology upgrades. Additionally, the tutorial on creating a Debian package and mirror has been updated for better readability and practical context.

New blog post: ZEvent 2025 technical retrospective

• Added src/pages/blog/posts/retex-zevent2025.md, a detailed post covering system improvements, migration to Kubernetes, use of Rust, and lessons learned from supporting the ZEvent 2025 charity event. The post discusses the evolution of infrastructure, statistics collection, and operational reliability.

Improvements to Debian package/mirror tutorial

• Updated section heading from French to English for broader accessibility in src/pages/blog/posts/create-deb-package.md.
• Added a new section explaining real-world practices for signing and structuring Debian mirrors, clarifying the purpose of Release, InRelease, and Release.gpg files, and providing a practical example of mirror layout.