ECOSYSTEM.md: Add axum-kit and fix formatting inconsistencies

[4lkaid]

Motivation

Axum is a powerful and ergonomic web framework for Rust, but integrating it with common database and caching solutions like SQLx and Redis can sometimes require boilerplate code and additional setup. This can be a barrier for developers who want to quickly build robust web applications without spending too much time on infrastructure configuration.

By streamlining the integration and usage of Axum with SQLx and Redis, we aim to:

1. Reduce boilerplate code: Simplify the process of setting up database connections and Redis caching in Axum applications.
2. Improve developer experience: Provide a more intuitive and ergonomic API for working with SQLx and Redis, allowing developers to focus on building features rather than infrastructure.
3. Encourage best practices: Ensure that the integration follows best practices for connection pooling, error handling, and performance optimization.

This change will make Axum even more accessible to developers who want to build high-performance web applications with minimal friction.