chore(flake): dev shell setup via nix flake

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

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+.direnv

flake.lock

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+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1754725699,
+        "narHash": "sha256-iAcj9T/Y+3DBy2J0N+yF9XQQQ8IEb5swLFzs23CdP88=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "85dbfc7aaf52ecb755f87e577ddbe6dbbdbc1054",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+  };
+  outputs = {nixpkgs, ...}: let
+    systems = [
+      "x86_64-linux"
+      "aarch64-linux"
+      "x86_64-darwin"
+      "aarch64-darwin"
+    ];
+    forAllSystems = f:
+      nixpkgs.lib.genAttrs systems (system: let
+        pkgs = import nixpkgs {inherit system;};
+      in
+        f {
+          inherit (pkgs) lib stdenv;
+          inherit pkgs;
+        });
+  in {
+    devShells = forAllSystems ({pkgs, ...}: {
+      default = pkgs.mkShell {
+        CGO_ENABLED = "0";
+        hardeningDisable = ["all"];
+
+        buildInputs = with pkgs; [
+          # Go tools
+          go
+          golangci-lint
+          gofumpt
+          gotools
+          delve
+        ];
+      };
+    });
+  };
+}