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/date-fns/isBefore.cjs

@@ -0,0 +1,25 @@
+"use strict";
+exports.isBefore = isBefore;
+var _index = require("./toDate.cjs");
+
+/**
+ * @name isBefore
+ * @category Common Helpers
+ * @summary Is the first date before the second one?
+ *
+ * @description
+ * Is the first date before the second one?
+ *
+ * @param date - The date that should be before the other one to return true
+ * @param dateToCompare - The date to compare with
+ *
+ * @returns The first date is before the second date
+ *
+ * @example
+ * // Is 10 July 1989 before 11 February 1987?
+ * const result = isBefore(new Date(1989, 6, 10), new Date(1987, 1, 11))
+ * //=> false
+ */
+function isBefore(date, dateToCompare) {
+  return +(0, _index.toDate)(date) < +(0, _index.toDate)(dateToCompare);
+}