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/getDaysInMonth.cjs

@@ -0,0 +1,36 @@
+"use strict";
+exports.getDaysInMonth = getDaysInMonth;
+var _index = require("./constructFrom.cjs");
+var _index2 = require("./toDate.cjs");
+
+/**
+ * The {@link getDaysInMonth} function options.
+ */
+
+/**
+ * @name getDaysInMonth
+ * @category Month Helpers
+ * @summary Get the number of days in a month of the given date.
+ *
+ * @description
+ * Get the number of days in a month of the given date, considering the context if provided.
+ *
+ * @param date - The given date
+ * @param options - An object with options
+ *
+ * @returns The number of days in a month
+ *
+ * @example
+ * // How many days are in February 2000?
+ * const result = getDaysInMonth(new Date(2000, 1))
+ * //=> 29
+ */
+function getDaysInMonth(date, options) {
+  const _date = (0, _index2.toDate)(date, options?.in);
+  const year = _date.getFullYear();
+  const monthIndex = _date.getMonth();
+  const lastDayOfMonth = (0, _index.constructFrom)(_date, 0);
+  lastDayOfMonth.setFullYear(year, monthIndex + 1, 0);
+  lastDayOfMonth.setHours(0, 0, 0, 0);
+  return lastDayOfMonth.getDate();
+}