refactor(hosts): move host configurations into folders

hosts/penguin/default.nix

@@ -0,0 +1,19 @@
+{ self, ... }:
+{
+  perSystem =
+    {
+      self',
+      pkgs,
+      lib,
+      ...
+    }:
+    {
+      packages.penguin = self.lib.mkOpenwrtImage {
+        inherit pkgs;
+        hostname = "penguin";
+        timezone = "Europe/Berlin";
+        ipaddr = "192.168.0.1";
+        packages = [ "ds-lite" ];
+      };
+    };
+}