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/endOfToday.d.cts

@@ -0,0 +1,30 @@
+import type { ContextOptions } from "./types.js";
+/**
+ * The {@link endOfToday} function options.
+ */
+export interface EndOfTodayOptions<DateType extends Date = Date>
+  extends ContextOptions<DateType> {}
+/**
+ * @name endOfToday
+ * @category Day Helpers
+ * @summary Return the end of today.
+ * @pure false
+ *
+ * @description
+ * Return the end of today.
+ *
+ * @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
+ * @typeParam ResultDate - The result `Date` type, it is the type returned from the context function if it is passed, or inferred from the arguments.
+ *
+ * @param options - The options
+ *
+ * @returns The end of today
+ *
+ * @example
+ * // If today is 6 October 2014:
+ * const result = endOfToday()
+ * //=> Mon Oct 6 2014 23:59:59.999
+ */
+export declare function endOfToday<ResultDate extends Date = Date>(
+  options?: EndOfTodayOptions<ResultDate>,
+): ResultDate;