Introduce Nix flake for streamlined project management

[SilverCoder]

Description

This pull request introduces a Nix flake to the project, aimed at enhancing project organization and reproducibility. The flake generates several essential components:

• A package facilitating streamlined deployment.
• An overlay to enhance compatibility and customization.
• An application for updating the yarn.nix file, ensuring seamless dependency management.
• A development shell for an efficient and consistent development environment.

Changes Made

• Added a Nix flake configuration file (flake.nix).
• Included necessary scripts and configurations for generating the yarn.nix file.
• Provided instructions on how to use the Nix flake in project configurations.
• Updated .gitignore to ignore Nix-related build artifacts (result).
• Added new files (flake.lock, package.nix, yarn.lock, yarn.nix).
• Updated existing files (assets/template.md, bunfig.toml).

Usage Instructions

• To use this flake in your configuration, add it as an input in your flake.nix file.
• Utilize the provided outputs for managing dependencies, checks, and development environments efficiently.
• Follow the provided instructions in the updated documentation (assets/template.md) for using Nix in the project.

[Philipp-M]

Left a few comments, I think when they're handled, it's looking good to me. (Tested and works for me otherwise)

[georgealexanderday]

This is the only way I've been able to install it and it works flawlessly - appreciate the work here. Would be great to get it in.