actions/checkout v4 -> v7, actions/setup-node v4 -> v7,
actions/upload-artifact v4 -> v7 across all workflows.
shivammathur/setup-php stays on the floating @v2 tag, which already
resolves to the latest 2.x release.
Ports the standalone due-date cron script into a proper Nextcloud 34
app with a personal-settings UI, per-user workflow configuration
(source/target stack, assigned-user and label filters, email
notification), a TimedJob background runner, and Gitea CI pipelines.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>