Minimum time between bookings not respected [appointments]

Steps to reproduce

1. Create a appointment schedule with a set "minimum time before next available slot", such as 2h (planning restrictions section)
2. Using the booking link, make and confirm a meeting
3. Observe the booking being added to the calendar
4. Open the booking link again, observe a slot directly after the first is available, book and confirm it
5. Observe two meetings directly after each other have been added to calendar

Expected behavior

If a 2h minimum time between meetings is set, next available slot should be 2h after the previously confirmed one, and it should not be possible to book a earlier slot in case the link was opened simultaneously (after the first is confirmed).

Actual behavior

Currently "minimum time before next available slot" is not respected at all.

Calendar app version

6.2.2

CalDAV-clients used

None, webui

Server operating system

Opensuse Leap

Web server

Apache

Database engine version

MariaDB

PHP engine version

PHP 8.3

Nextcloud version

32.0.8

Updated from an older installed version or fresh install

Updated from an older version

Web server error log

No errors emmited by bug

Other information is added if needed!

Start by tracing the booking-link appointment flow described in the reproduction steps, including how availability is calculated after a confirmed meeting and how simultaneous bookings are handled. Confirm the fix by reproducing the two-hour restriction and verifying that an earlier overlapping slot cannot be booked.