Allow hosts to manually add early check-in/late check-out upsells for guests

Currently, early check-in and late check-out upsells can only be purchased by the guest via the Guest Portal. Hosts are requesting the ability to manually apply these upsells to a reservation on the guest's behalf to provide a more convenient experience. This is especially important as the AI agent may incorrectly inform guests that the host can handle this for them, creating confusion when the host is then unable to do so.