feat: add openapi design doc

Caddyfile

@@ -0,0 +1,15 @@
+http://localhost
+
+route /api/v1/* {
+    uri strip_prefix /api/v1
+    reverse_proxy app
+}
+
+route /docs/* {
+    uri strip_prefix /docs
+    file_server {
+        root /usr/share/caddy/www/design
+        index index.html
+        browse true
+    }
+}