added install script and git config

install.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+echo "==> Checking for Nix..."
+if ! command -v nix >/dev/null 2>&1; then
+    echo "==> Installing Nix vis Determinate Systems installer..."
+    curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install
+    . /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
+else
+    echo "Nix already installed, skipping."
+fi
+
+echo "==> Copying config to /etc/nix-darwin..."
+sudo mkdir -p /etc/nix-darwin
+sudo cp -r . /etc/nix-darwin
+sudo chown -R root:wheel /etc/nix-darwin
+
+echo "==> Renaming conflicting shell files if present..."
+[ -f /etc/bashrc ] && sudo mv /etc/bashrc /etc/bashrc.before-nix-darwin
+[ -f /etc/zshrc ] && sudo mv /etc/zshrc /etc/zshrc.before-nix-darwin
+[ -f /etc/zshenv ] && sudo mv /etc/zshenv /etc/zshenv.before-nix-darwin
+
+echo "==> Bootstraping nix-darwin..."
+nix run nix-darwin/master#darwin-rebuild -- switch --flake /etc/nix-darwin
+
+echo "==> Done! Restart your terminal to apply all changes."