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/differenceInISOWeekYears.cjs

@@ -0,0 +1,65 @@
+"use strict";
+exports.differenceInISOWeekYears = differenceInISOWeekYears;
+var _index = require("./_lib/normalizeDates.cjs");
+var _index2 = require("./compareAsc.cjs");
+var _index3 = require("./differenceInCalendarISOWeekYears.cjs");
+var _index4 = require("./subISOWeekYears.cjs");
+
+/**
+ * The {@link differenceInISOWeekYears} function options.
+ */
+
+/**
+ * @name differenceInISOWeekYears
+ * @category ISO Week-Numbering Year Helpers
+ * @summary Get the number of full ISO week-numbering years between the given dates.
+ *
+ * @description
+ * Get the number of full ISO week-numbering years 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 - The options
+ *
+ * @returns The number of full ISO week-numbering years
+ *
+ * @example
+ * // How many full ISO week-numbering years are between 1 January 2010 and 1 January 2012?
+ * const result = differenceInISOWeekYears(
+ *   new Date(2012, 0, 1),
+ *   new Date(2010, 0, 1)
+ * )
+ * // => 1
+ */
+function differenceInISOWeekYears(laterDate, earlierDate, options) {
+  const [laterDate_, earlierDate_] = (0, _index.normalizeDates)(
+    options?.in,
+    laterDate,
+    earlierDate,
+  );
+
+  const sign = (0, _index2.compareAsc)(laterDate_, earlierDate_);
+  const diff = Math.abs(
+    (0, _index3.differenceInCalendarISOWeekYears)(
+      laterDate_,
+      earlierDate_,
+      options,
+    ),
+  );
+
+  const adjustedDate = (0, _index4.subISOWeekYears)(
+    laterDate_,
+    sign * diff,
+    options,
+  );
+
+  const isLastISOWeekYearNotFull = Number(
+    (0, _index2.compareAsc)(adjustedDate, earlierDate_) === -sign,
+  );
+  const result = sign * (diff - isLastISOWeekYearNotFull);
+
+  // Prevent negative zero
+  return result === 0 ? 0 : result;
+}