feat: rewrite pi to be simple and nix based

pi/configuration.nix

@@ -0,0 +1,39 @@
+{ config, pkgs, ... }:
+
+{
+  system.stateVersion = "24.11";
+
+  networking.hostName = "noisebell";
+
+  # Enable the noisebell service
+  services.noisebell = {
+    enable = true;
+    endpointUrl = "https://example.com/webhook"; # TODO: set your endpoint
+  };
+
+  # Basic system config
+  nix.settings.experimental-features = [ "nix-command" "flakes" ];
+
+  # Tailscale
+  services.tailscale.enable = true;
+
+  # Caddy reverse proxy — proxies to the noisebell status endpoint
+  services.caddy = {
+    enable = true;
+    virtualHosts.":80".extraConfig = ''
+      reverse_proxy localhost:${toString config.services.noisebell.port}
+    '';
+  };
+
+  services.openssh.enable = true;
+
+  # Only allow traffic from Tailscale interface
+  networking.firewall = {
+    trustedInterfaces = [ "tailscale0" ];
+    allowedUDPPorts = [ config.services.tailscale.port ];
+  };
+
+  users.users.root.openssh.authorizedKeys.keys = [
+    # TODO: add your SSH public key
+  ];
+}