refactor: move system modules into proper directories

systems/modules/networking.nix

@@ -0,0 +1,32 @@
+{ hostname, lib, ... }:
+{
+  networking = {
+    hostName = hostname;
+    useDHCP = lib.mkDefault true;
+    networkmanager.enable = true;
+    networkmanager.wifi.backend = "iwd";
+
+    # Configures a simple stateful firewall.
+    # By default, it doesn't allow any incoming connections.
+    firewall = {
+      enable = true;
+      allowedTCPPorts = [
+        22 # SSH
+      ];
+      allowedUDPPorts = [ ];
+    };
+
+    interfaces.enp12s0.wakeOnLan.policy = [
+      "phy"
+      "unicast"
+      "multicast"
+      "broadcast"
+      "arp"
+      "magic"
+      "secureon"
+    ];
+    interfaces.enp12s0.wakeOnLan.enable = true;
+  };
+  services.openssh.enable = true;
+  services.tailscale.enable = true;
+}