refactor(flake-parts): initial flake-parts configuration

inputs/system/modules/base/networking/firewall/default.nix

@@ -0,0 +1,18 @@
+{ lib, config, ... }:
+
+let
+  inherit (lib) mkIf;
+  host = config.systemModules.host;
+in
+
+{
+  config = mkIf (host.type != "phone") {
+    networking.firewall = {
+      enable = true;
+      allowedTCPPorts = [
+        443 # https
+        57621 # spotify
+      ];
+    };
+  };
+}