feat(auth): wire root barrel + ui/query stub

packages/auth/src/index.ts

@@ -1 +1,10 @@
-export {};
+export type { User } from "./entities/user";
+export type { Session } from "./entities/session";
+export type { Cookie } from "./entities/cookie";
+export {
+  AuthenticationError,
+  UnauthenticatedError,
+  UnauthorizedError,
+  InputParseError,
+} from "./entities/errors";
+export { SESSION_COOKIE } from "./config";

packages/auth/src/ui/query.ts

@@ -0,0 +1,5 @@
+// React Query option builders for auth feature procedures.
+// Sign-in/up/out are mutations — no query options needed.
+// This file is intentionally minimal; expand if read procedures get added.
+
+export {};