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/parse/_lib/Parser.cjs

@@ -0,0 +1,28 @@
+"use strict";
+exports.Parser = void 0;
+var _Setter = require("./Setter.cjs");
+
+class Parser {
+  run(dateString, token, match, options) {
+    const result = this.parse(dateString, token, match, options);
+    if (!result) {
+      return null;
+    }
+
+    return {
+      setter: new _Setter.ValueSetter(
+        result.value,
+        this.validate,
+        this.set,
+        this.priority,
+        this.subPriority,
+      ),
+      rest: result.rest,
+    };
+  }
+
+  validate(_utcDate, _value, _options) {
+    return true;
+  }
+}
+exports.Parser = Parser;