Add pre-commit hook to run gitleaks

Search for accidentally included secrets when committing

.envrc

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

.pre-commit-config.yaml

@@ -0,0 +1,5 @@
+repos:
+  - repo: https://github.com/gitleaks/gitleaks
+    rev: v8.18.4
+    hooks:
+      - id: gitleaks

flake.nix

@@ -85,7 +85,8 @@
       pkgs = import nixpkgs {system = "x86_64-linux";};
     in
       pkgs.mkShellNoCC {
-        packages = [pkgs.nil];
+        packages = with pkgs; [nil pre-commit];
+        shellHook = "pre-commit install --install-hooks";
       };
     homeConfigurations = {
       # Server