docs: add best practices documentation for Tux development

- Introduce comprehensive best practices across various aspects of Tux development, including async programming, error handling, logging, caching, CI/CD, code review, debugging, and documentation standards.
- Enhance developer resources with structured guidelines to improve code quality, maintainability, and collaboration.
- Update the index to reflect the new documentation structure and ensure easy navigation for contributors.

Author: kzndotsh

docs/content/developer/best-practices/async.md

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+---
+title: Caching Best Practices
+---
+
+Caching best practices for Tux development, including cache invalidation, cache expiration, and cache eviction.
+
+Caching has not been implemented yet, so this section is placeholder. In the future, Redis or Valkey will be used for caching.
+
+Some patterns of caching have been implemented across the codebase for smaller use cases but they are not yet properly documented.