feat: refactor caddie to use external mappings and add example mappings

mappings.example.ts

@@ -0,0 +1,15 @@
+const mappings = {
+  // redirects
+  "http://ip": "redir:https://example.com{uri}",
+
+  // reverse proxies
+  "example.com": "http://localhost:8080",
+
+  // static files
+  "foo.example.com": "/opt/sites/foo",
+
+  // keys
+  "ssh.example.com": "key:ssh-ed25519 qwerty1234567890 example.com",
+}
+
+export default mappings;