dev: direnv + flake for nix-shell

Change-Id: Ic74d9f5e0529d550581d8ff96bdace74cb39b76f
diff --git a/.envrc b/.envrc
new file mode 100644
index 0000000..b62b6ac
--- /dev/null
+++ b/.envrc
@@ -0,0 +1,5 @@
+# shellcheck shell=bash
+
+use flake
+
+export KUBECONFIG=$(pwd)/priv/kubeconfig-hetzner-new.yaml