chore: migrate from nix flakes to devbox

Development environment setup is now managed using devbox instead of nix flakes.
Both solutions provide similar tooling (go, just, kubectl, etc.) but with different
management approach.

Signed-off-by: suin <[email protected]>

Author: suin

.envrc

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+# Automatically sets up your devbox environment whenever you cd into this
+# directory via our direnv integration:
+
+eval "$(devbox generate direnv --print-envrc)"
+
+# check out https://www.jetpack.io/devbox/docs/ide_configuration/direnv/
+# for more details
+export KUBECONFIG="$(pwd)/.kube"

CONTRIBUTING.md

@@ -3,8 +3,8 @@
 ## Development Environment Setup
 
 ### Prerequisites
-- [Nix](https://nixos.org) package manager
-- Nix flakes enabled
+- [Devbox](https://www.jetpack.io/devbox/) - Development environment manager
+- [direnv](https://direnv.net/) (recommended for automatic environment activation)
 
 ### Setting Up Development Environment
 
@@ -16,12 +16,18 @@
 
 2. Enter development shell:
    ```bash
-   nix develop
+   devbox shell
    ```
+   Or if you have direnv installed and enabled:
+   ```bash
+   direnv allow
+   ```
+   
    This will make the following tools available:
    - Go
    - Bun
    - Biome
+   - just
    - kind
    - kubectl
 

devbox.json

@@ -0,0 +1,21 @@
+{
+  "$schema": "https://raw.githubusercontent.com/jetify-com/devbox/0.14.0/.schema/devbox.schema.json",
+  "packages": [
+    "bun@latest",
+    "biome@latest",
+    "go@latest",
+    "just@latest",
+    "kind@latest",
+    "kubectl@latest"
+  ],
+  "shell": {
+    "init_hook": [
+      "echo 'Welcome to devbox!' > /dev/null"
+    ],
+    "scripts": {
+      "test": [
+        "echo \"Error: no test specified\" && exit 1"
+      ]
+    }
+  }
+}