Nextcloud 19.0-2: background jobs and upload fixes

Changes:

• Update Nextcloud to 34.0.5 and use the supported Debian PHP 8.4 runtime.
• Restore scheduled background jobs and normal administrator settings.
• Preserve configuration-file protection through supported updates.
• Fix Apache rules that blocked chunked uploads.
• Fix Let’s Encrypt credential setup and DNS resolution with static IP addresses.
• Keep failed first-boot setup retryable and correct installer-media removal and backup authentication.

Links

• Nextcloud server image
• Release files and checksums