fix: export missing type from anonymous identity hook (#527)

Author: michalkvasnicak

.changeset/old-pumas-call.md

@@ -0,0 +1,5 @@
+---
+"@frames.js/render": patch
+---
+
+fix(@frames.js/render): export missing type for anonymous signer

packages/render/src/identity/anonymous/index.ts

@@ -1,5 +1,6 @@
 export {
   type AnonymousFrameContext,
   type AnonymousSigner,
+  type AnonymousSignerInstance,
   useAnonymousIdentity,
 } from "./use-anonymous-identity";