Planify crashes when connecting to NextCloud CalDAV, tries to use non-existent OAuth endpoint

[cosmic-hobo]

Describe the bug

Planify crashes immediately after attempting to sync with NextCloud AND CalDAV
After crash, cannot reopen Planify until data is reset
Fresh install works until NextCloud connection is attempted

To Reproduce
Steps to reproduce the behavior:

1. Go to
2. Click on 'Acccounts' add Nextcloud or Caldav
3. Enter login credentials in browser
4. Crashes as soon as login is granted to planify

Expected behavior
Connects to calendars/lists on my Nextcloud

Desktop (please complete the following information):

• Gnome on Linux Debian 12

Root Cause Identified:
Debug logs show Planify attempts to connect to /login/v2/poll OAuth endpoint
This endpoint returns HTTP 404 on the NextCloud instance
The OAuth attempt happens even when using basic authentication with app passwords

Evidence:
libsoup-http2-DEBUG shows repeated 404 errors for cloud.freiheitswolke.org/login/v2/poll
Database examination shows CalDAV configuration exists but Planify still attempts OAuth flow
Issue is reproducible and consistent