A workflow now belongs to whoever owns its board. The settings page
lists, edits and deletes workflows by board ownership alone, using
Deck's BoardMapper::findAllByOwner(), a single owner query that never
returns shared boards and carries no frozen uid. A transferred board's
workflows therefore show up for the new owner immediately.
The background job still needs one user to run as and mail, so it
looks up the board owner before every run and stores it in user_id
when it changed. Archived boards stay listed so their workflows keep
a name, but are no longer offered or accepted as a target.
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>