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/nextMonday.d.cts

@@ -0,0 +1,34 @@
+import type { ContextOptions, DateArg } from "./types.js";
+/**
+ * The {@link nextMonday} function options.
+ */
+export interface NextMondayOptions<DateType extends Date = Date>
+  extends ContextOptions<DateType> {}
+/**
+ * @name nextMonday
+ * @category Weekday Helpers
+ * @summary When is the next Monday?
+ *
+ * @description
+ * When is the next Monday?
+ *
+ * @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, returned from the context function if passed, or inferred from the arguments.
+ *
+ * @param date - The date to start counting from
+ * @param options - An object with options
+ *
+ * @returns The next Monday
+ *
+ * @example
+ * // When is the next Monday after Mar, 22, 2020?
+ * const result = nextMonday(new Date(2020, 2, 22))
+ * //=> Mon Mar 23 2020 00:00:00
+ */
+export declare function nextMonday<
+  DateType extends Date,
+  ResultDate extends Date = DateType,
+>(
+  date: DateArg<DateType>,
+  options?: NextMondayOptions<ResultDate> | undefined,
+): ResultDate;