Add OpenAPI docs, frontend, migrations, and API updates

- OpenAPI: add missing endpoints (add-from-url, subscriptions, public availability)
- OpenAPI: CalendarSubscription schema, Subscriptions tag
- Frontend app
- Migrations: count_for_availability, subscriptions_sync, user_preferences, calendar_settings
- Config, rate limit, auth, calendar, booking, ICS, availability, user service updates

Made-with: Cursor

frontend/node_modules/react-router-dom/dist/index.mjs

@@ -0,0 +1,18 @@
+/**
+ * react-router-dom v7.13.1
+ *
+ * Copyright (c) Remix Software Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE.md file in the root directory of this source tree.
+ *
+ * @license MIT
+ */
+
+// index.ts
+import { HydratedRouter, RouterProvider } from "react-router/dom";
+export * from "react-router";
+export {
+  HydratedRouter,
+  RouterProvider
+};