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/differenceInCalendarWeeks.d.cts

@@ -0,0 +1,50 @@
+import type {
+  ContextOptions,
+  DateArg,
+  LocalizedOptions,
+  WeekOptions,
+} from "./types.js";
+/**
+ * The {@link differenceInCalendarWeeks} function options.
+ */
+export interface DifferenceInCalendarWeeksOptions
+  extends LocalizedOptions<"options">,
+    WeekOptions,
+    ContextOptions<Date> {}
+/**
+ * @name differenceInCalendarWeeks
+ * @category Week Helpers
+ * @summary Get the number of calendar weeks between the given dates.
+ *
+ * @description
+ * Get the number of calendar weeks between the given dates.
+ *
+ * @param laterDate - The later date
+ * @param earlierDate - The earlier date
+ * @param options - An object with options.
+ *
+ * @returns The number of calendar weeks
+ *
+ * @example
+ * // How many calendar weeks are between 5 July 2014 and 20 July 2014?
+ * const result = differenceInCalendarWeeks(
+ *   new Date(2014, 6, 20),
+ *   new Date(2014, 6, 5)
+ * )
+ * //=> 3
+ *
+ * @example
+ * // If the week starts on Monday,
+ * // how many calendar weeks are between 5 July 2014 and 20 July 2014?
+ * const result = differenceInCalendarWeeks(
+ *   new Date(2014, 6, 20),
+ *   new Date(2014, 6, 5),
+ *   { weekStartsOn: 1 }
+ * )
+ * //=> 2
+ */
+export declare function differenceInCalendarWeeks(
+  laterDate: DateArg<Date> & {},
+  earlierDate: DateArg<Date> & {},
+  options?: DifferenceInCalendarWeeksOptions | undefined,
+): number;