checkpoint: implement wgcloak v1 foundations

examples/client.minimal.toml

@@ -0,0 +1,13 @@
+# Minimal client. Replace the hostname, id, and secret path before use.
+# The secret file must contain a generated secret and be mode 0600.
+
+[client]
+server = "vpn.example.invalid"
+id = "replace-me"
+secret_file = "/etc/wgcloak/client.secret"
+
+[local]
+listen = "127.0.0.1:51821"
+
+[transport]
+mode = "auto"