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/getISOWeekYear.d.ts

@@ -0,0 +1,29 @@
+import type { ContextOptions, DateArg } from "./types.js";
+/**
+ * The {@link getISOWeekYear} function options.
+ */
+export interface GetISOWeekYearOptions extends ContextOptions<Date> {}
+/**
+ * @name getISOWeekYear
+ * @category ISO Week-Numbering Year Helpers
+ * @summary Get the ISO week-numbering year of the given date.
+ *
+ * @description
+ * Get the ISO week-numbering year of the given date,
+ * which always starts 3 days before the year's first Thursday.
+ *
+ * ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
+ *
+ * @param date - The given date
+ *
+ * @returns The ISO week-numbering year
+ *
+ * @example
+ * // Which ISO-week numbering year is 2 January 2005?
+ * const result = getISOWeekYear(new Date(2005, 0, 2))
+ * //=> 2004
+ */
+export declare function getISOWeekYear(
+  date: DateArg<Date> & {},
+  options?: GetISOWeekYearOptions | undefined,
+): number;