refactor: hosts - darwin

hosts/darwin_fern/default.nix

@@ -0,0 +1,13 @@
+_:
+#############################################################
+#
+#  Fern - MacBook Pro 2022 13-inch M2 16G, mainly for business.
+#
+#############################################################
+let
+  hostname = "fern";
+in {
+  networking.hostName = hostname;
+  networking.computerName = hostname;
+  system.defaults.smb.NetBIOSName = hostname;
+}

hosts/darwin_fern/home.nix

@@ -0,0 +1,18 @@
+{
+  programs.ssh = {
+    enable = true;
+    extraConfig = ''
+      Host github.com
+        Hostname github.com
+        # github is controlled by fern~
+        IdentityFile ~/.ssh/fern
+        # Specifies that ssh should only use the identity file explicitly configured above
+        # required to prevent sending default identity files first.
+        IdentitiesOnly yes
+    '';
+  };
+
+  modules.editors.emacs = {
+    enable = true;
+  };
+}