Add Nix flake for Compact compiler

[solidsnakedev]

Adds Nix flake that provides compactc, compactc.bin, and zkir binaries per system.

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[solidsnakedev]

@gilescope what else do we need to get this approve?
is it because of CI Checkmarx failing?

Creating directory
flag needs an argument: --scs-repo-token
Error: flag needs an argument: --scs-repo-token
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[jonathanfishbein1]

Hi I'm really looking forward to this PR. Global user installation of the compiler toolchain is clunky. I was attampting to make use of this flake but was running into some issues. Ironically I think this doesn't quite work for use on NixOS. Here's a link discussing the quirks of NixOS with Midnight

https://forum.midnight.network/t/error-failed-to-run-compactc/500

I could be missing something. Let me know if and how I can assist

[Copilot]

Pull Request Overview

This PR adds Nix flake support to provide the Compact compiler toolchain for different systems. The implementation downloads and installs Compact developer tools in a project-local directory.

Key Changes:

• Adds a Nix flake configuration with multi-system support (x86_64-linux, x86_64-darwin, aarch64-darwin)
• Creates a dev shell that automatically installs and sets up the Compact compiler toolchain version 0.24.0
• Includes direnv configuration for automatic environment activation

Reviewed Changes

Copilot reviewed 2 out of 4 changed files in this pull request and generated 4 comments.

File	Description
flake.nix	Defines Nix flake with dev shell that downloads and configures Compact toolchain
.envrc	Adds direnv integration to automatically enter Nix development shell

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[Copilot]

The description mentions 'Example Counter' which appears to be a copy-paste error. It should describe the actual Compact compiler flake.

Suggested change

	description = "Example Counter – Nix flake that provides the Compact compiler per system";
	description = "Nix flake that provides the Compact compiler per system";

[solidsnakedev]

@jonathanfishbein1 I fixed it. This is a common problem in NixOS, most Linux distributions use bin/bash instead of #!/usr/bin/env bash. The solution is to patch the bash script used by compactc

If there are no more observations, I suggest we merge the PR? @gilescope @Olanetsoft