clanCore: install essential tools for debugging

nixosModules/clanCore/flake-module.nix

@@ -6,6 +6,7 @@
       ./zerotier
       ./meshnamed
       ./networking.nix
+      ./packages.nix
       inputs.sops-nix.nixosModules.sops
       # just some example options. Can be removed later
       ./vm.nix

nixosModules/clanCore/packages.nix

@@ -0,0 +1,10 @@
+{ pkgs, ... }: {
+  # essential debugging tools for networked services
+  environment.systemPackages = [
+    pkgs.dnsutils
+    pkgs.tcpdump
+    pkgs.curl
+    pkgs.jq
+    pkgs.htop
+  ];
+}