feat: allow multipart requests for public api

Adds support for multipart/form-data requests in the public api
allowing documents to be uploaded without having to perform a secondary
request.

Need to rollout further endpoints for envelopes and templates.

Need to change how we store files to not use `putFileServerSide`

packages/auth/package.json

@@ -20,6 +20,6 @@
     "luxon": "^3.5.0",
     "nanoid": "^5.1.5",
     "ts-pattern": "^5.0.5",
-    "zod": "3.24.1"
+    "zod": "^3.25.76"
   }
 }