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/differenceInCalendarISOWeeks.cjs

@@ -0,0 +1,59 @@
+"use strict";
+exports.differenceInCalendarISOWeeks = differenceInCalendarISOWeeks;
+var _index = require("./_lib/getTimezoneOffsetInMilliseconds.cjs");
+var _index2 = require("./_lib/normalizeDates.cjs");
+var _index3 = require("./constants.cjs");
+var _index4 = require("./startOfISOWeek.cjs");
+
+/**
+ * The {@link differenceInCalendarISOWeeks} function options.
+ */
+
+/**
+ * @name differenceInCalendarISOWeeks
+ * @category ISO Week Helpers
+ * @summary Get the number of calendar ISO weeks between the given dates.
+ *
+ * @description
+ * Get the number of calendar ISO weeks between the given dates.
+ *
+ * ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
+ *
+ * @param laterDate - The later date
+ * @param earlierDate - The earlier date
+ * @param options - An object with options
+ *
+ * @returns The number of calendar ISO weeks
+ *
+ * @example
+ * // How many calendar ISO weeks are between 6 July 2014 and 21 July 2014?
+ * const result = differenceInCalendarISOWeeks(
+ *   new Date(2014, 6, 21),
+ *   new Date(2014, 6, 6),
+ * );
+ * //=> 3
+ */
+function differenceInCalendarISOWeeks(laterDate, earlierDate, options) {
+  const [laterDate_, earlierDate_] = (0, _index2.normalizeDates)(
+    options?.in,
+    laterDate,
+    earlierDate,
+  );
+
+  const startOfISOWeekLeft = (0, _index4.startOfISOWeek)(laterDate_);
+  const startOfISOWeekRight = (0, _index4.startOfISOWeek)(earlierDate_);
+
+  const timestampLeft =
+    +startOfISOWeekLeft -
+    (0, _index.getTimezoneOffsetInMilliseconds)(startOfISOWeekLeft);
+  const timestampRight =
+    +startOfISOWeekRight -
+    (0, _index.getTimezoneOffsetInMilliseconds)(startOfISOWeekRight);
+
+  // Round the number of weeks to the nearest integer because the number of
+  // milliseconds in a week is not constant (e.g. it's different in the week of
+  // the daylight saving time clock shift).
+  return Math.round(
+    (timestampLeft - timestampRight) / _index3.millisecondsInWeek,
+  );
+}