feat(dav): allow muting reminders per calendar

[SoleroTG]

Summary

Adds the CalDAV property {http://nextcloud.com/ns}ignore-reminders to calendars and dav_shares database tables to allow users to mute background event notifications (email and push) on a per-calendar basis.

• Resolves: Disable or enable notifications on a per calendar basis calendar#6390
• Requires: feat(calendar): parse {http://nextcloud.com/ns}disable-alarm-notifications property cdav-library#1088
• Requires: feat(calendars): add per-calendar notification muting toggle calendar#8796

• Migration Version1038Date20260828000000 adding ignore_reminders boolean columns to calendars and dav_shares.
• WebDAV PROPPATCH/PROPFIND handling in CalDavBackend.php.
• Per-recipient filtering in ReminderService.php ensuring independent muting for owners and sharees.
• Unit tests added in CalDavBackendTest.php.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests are included
• Screenshots before/after for front-end changes
• Documentation has been updated or is not required

AI (if applicable)

• The content of this PR was partly or fully generated using AI

[SebastianKrupinski]

Hi @SoleroTG

Thank you for the PR. But please put back the original PR description and modify the information

Also can you rebase your changes on the latest master please

[SebastianKrupinski]

Hi @SoleroTG

I fixed this PR for you, as it was just easier then explaining it, in multiple back and forth conversations. Your AI agent implemented this completely wrong.

I did make some comments in the calendar PR, which you can fix.

[SoleroTG]

Hi @SebastianKrupinski, thanks for fixing this.

I adjusted my nextcloud pipeline to pay more attention next time.

[SebastianKrupinski]

@ChristophWurst @DerDreschner @odzhychko @hamza221

Can I get a second on this please