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/getWeeksInMonth.js

@@ -0,0 +1,46 @@
+import { differenceInCalendarWeeks } from "./differenceInCalendarWeeks.js";
+import { lastDayOfMonth } from "./lastDayOfMonth.js";
+import { startOfMonth } from "./startOfMonth.js";
+import { toDate } from "./toDate.js";
+
+/**
+ * The {@link getWeeksInMonth} function options.
+ */
+
+/**
+ * @name getWeeksInMonth
+ * @category Week Helpers
+ * @summary Get the number of calendar weeks a month spans.
+ *
+ * @description
+ * Get the number of calendar weeks the month in the given date spans.
+ *
+ * @param date - The given date
+ * @param options - An object with options.
+ *
+ * @returns The number of calendar weeks
+ *
+ * @example
+ * // How many calendar weeks does February 2015 span?
+ * const result = getWeeksInMonth(new Date(2015, 1, 8))
+ * //=> 4
+ *
+ * @example
+ * // If the week starts on Monday,
+ * // how many calendar weeks does July 2017 span?
+ * const result = getWeeksInMonth(new Date(2017, 6, 5), { weekStartsOn: 1 })
+ * //=> 6
+ */
+export function getWeeksInMonth(date, options) {
+  const contextDate = toDate(date, options?.in);
+  return (
+    differenceInCalendarWeeks(
+      lastDayOfMonth(contextDate, options),
+      startOfMonth(contextDate, options),
+      options,
+    ) + 1
+  );
+}
+
+// Fallback for modularized imports:
+export default getWeeksInMonth;